Imported from David-Li0406/meta-skill-evloving (skill-flow/data/skills-refined-36k/skillsmp/building-agents-construction/SKILL.md). Install upstream with npx skills add David-Li0406/meta-skill-evloving --skill building-agents-construction. Copyright stays with the author (Apache-2.0).

Building Agents - Construction Process

Step-by-step guide for building goal-driven agent packages.

Prerequisites: Read building-agents-core for fundamental concepts.

Reference Example: Online Research Agent

A complete, working agent example is included in this skill folder:

Location: examples/online_research_agent/

This agent demonstrates:

Proper node type usage (llm_generate vs llm_tool_use)
Correct tool declaration (only uses available MCP tools)
MCP server configuration
Multi-step workflow with 8 nodes
Quality checking and file output

Study this example before building your own agent.

CRITICAL: Register hive-tools MCP Server FIRST

⚠️ MANDATORY FIRST STEP: Always register the hive-tools MCP server before building any agent.

# MANDATORY: Register hive-tools MCP server BEFORE building any agent
# cwd path is relative to project root (where you run Claude Code from)
mcp__agent-builder__add_mcp_server(
    name="hive-tools",
    transport="stdio",
    command="python",
    args='["mcp_server.py", "--stdio"]',
    cwd="tools",  # Relative to project root
    description="Hive tools MCP server with web search, file operations, etc."
)
# Returns: 12 tools available including web_search, web_scrape, pdf_read,
# view_file, write_to_file, list_dir, replace_file_content, apply_diff,
# apply_patch, grep_search, execute_command_tool, example_tool

Then discover what tools are available:

# After registering, verify tools are available
mcp__agent-builder__list_mcp_servers()  # Should show hive-tools
mcp__agent-builder__list_mcp_tools()    # Should show 12 tools

CRITICAL: Discover Available Tools

⚠️ The #1 cause of agent failures is using tools that don't exist.

Before building ANY node that uses tools, you MUST have already registered the MCP server above, then verify:

Lessons learned from production failures:

Load hive/tools MCP server before building agents - The tools must be registered before you can use them
Only use available MCP tools on agent nodes - Do NOT invent or assume tools exist
Verify each tool name exactly - Tool names are case-sensitive and must match exactly

Example from online_research_agent:

# CORRECT: Node uses only tools that exist in hive-tools MCP server
search_sources_node = NodeSpec(
    id="search-sources",
    node_type="llm_tool_use",  # This node USES tools
    tools=["web_search"],       # This tool EXISTS in hive-tools
    ...
)

# WRONG: Invented tool that doesn't exist
bad_node = NodeSpec(
    id="bad-node",
    node_type="llm_tool_use",
    tools=["read_excel"],  # ❌ This tool doesn't exist - agent will fail!
    ...
)

Node types and tool requirements:

Node Type	Tools	When to Use
`llm_generate`	`tools=[]`	Pure LLM reasoning, JSON output
`llm_tool_use`	`tools=["web_search", ...]`	Needs to call external tools
`router`	`tools=[]`	Conditional branching
`function`	`tools=[]`	Python function execution

CRITICAL: entry_points Format Reference

⚠️ Common Mistake Prevention:

The entry_points parameter in GraphSpec has a specific format that is easy to get wrong. This section exists because this mistake has caused production bugs.

Correct Format

entry_points = {"start": "first-node-id"}

Examples from working agents:

# From exports/outbound_sales_agent/agent.py
entry_node = "lead-qualification"
entry_points = {"start": "lead-qualification"}

# From exports/support_ticket_agent/agent.py (FIXED)
entry_node = "parse-ticket"
entry_points = {"start": "parse-ticket"}

WRONG Formats (DO NOT USE)

# ❌ WRONG: Using node ID as key with input keys as value
entry_points = {
    "parse-ticket": ["ticket_content", "customer_id", "ticket_id"]
}
# Error: ValidationError: Input should be a valid string, got list

# ❌ WRONG: Using set instead of dict
entry_points = {"parse-ticket"}
# Error: ValidationError: Input should be a valid dictionary, got set

# ❌ WRONG: Missing "start" key
entry_points = {"entry": "parse-ticket"}
# Error: Graph execution fails, cannot find entry point

Validation Check

After writing graph configuration, ALWAYS validate:

# Check 1: Must be a dict
assert isinstance(entry_points, dict), f"entry_points must be dict, got {type(entry_points)}"

# Check 2: Must have "start" key
assert "start" in entry_points, f"entry_points must have 'start' key, got keys: {entry_points.keys()}"

# Check 3: "start" value must match entry_node
assert entry_points["start"] == entry_node, f"entry_points['start']={entry_points['start']} must match entry_node={entry_node}"

# Check 4: Value must be a string (node ID)
assert isinstance(entry_points["start"], str), f"entry_points['start'] must be string, got {type(entry_points['start'])}"

Why this matters: GraphSpec uses Pydantic validation. The wrong format causes ValidationError at runtime, which blocks all agent execution and tests. This bug is not caught until you try to run the agent.

AgentRuntime Architecture

All agents use AgentRuntime for execution. This provides:

Multi-entrypoint support: Multiple entry points for different triggers
HITL (Human-in-the-Loop): Pause/resume for user input
Session state management: Memory persists across pause/resume cycles
Concurrent executions: Handle multiple requests in parallel

Key Components

from framework.runtime.agent_runtime import AgentRuntime, create_agent_runtime
from framework.runtime.execution_stream import EntryPointSpec

Entry Point Specs

Each entry point requires an EntryPointSpec:

def _build_entry_point_specs(self) -> list[EntryPointSpec]:
    specs = []
    for ep_id, node_id in self.entry_points.items():
        if ep_id == "start":
            trigger_type = "manual"
        elif "_resume" in ep_id:
            trigger_type = "resume"
        else:
            trigger_type = "manual"

        specs.append(EntryPointSpec(
            id=ep_id,
            name=ep_id.replace("-", " ").title(),
            entry_node=node_id,
            trigger_type=trigger_type,
            isolation_level="shared",
        ))
    return specs

HITL Pause/Resume Pattern

For agents that need user input mid-execution:

Define pause nodes in graph config:

pause_nodes = ["ask-clarifying-questions"]  # Execution pauses here

Define resume entry points:

entry_points = {
    "start": "first-node",
    "ask-clarifying-questions_resume": "process-response",  # Resume point
}

Pass session_state on resume:

# When resuming, pass session_state separately from input_data
result = await agent.trigger_and_wait(
    entry_point="ask-clarifying-questions_resume",
    input_data={"user_response": "user's answer"},
    session_state=previous_result.session_state,  # Contains memory
)

CRITICAL: session_state must be passed as a separate parameter, NOT merged into input_data. The executor restores memory from session_state["memory"].

LLM Provider Configuration

Default: All agents use LiteLLM with Cerebras as the primary provider for cost-effective, high-performance inference.

Environment Setup

Set your Cerebras API key:

export CEREBRAS_API_KEY="your-api-key-here"

Or configure via aden_tools credentials:

# Store credential
aden credentials set cerebras YOUR_API_KEY

Model Configuration

Default model in config.py:

model: str = "cerebras/zai-glm-4.7"  # Fast, cost-effective

Supported Providers via LiteLLM

The framework uses LiteLLM, which supports multiple providers. Priority order:

Cerebras (default) - cerebras/zai-glm-4.7
OpenAI - gpt-4o-mini, gpt-4o
Anthropic - claude-haiku-4-5-20251001, claude-sonnet-4-5-20250929
Local - ollama/llama3

To use a different provider, change the model in config.py and ensure the corresponding API key is available:

Cerebras: CEREBRAS_API_KEY or aden credentials set cerebras
OpenAI: OPENAI_API_KEY or aden credentials set openai
Anthropic: ANTHROPIC_API_KEY or aden credentials set anthropic

Building Session Management with MCP

MANDATORY: Use the agent-builder MCP server's BuildSession system for automatic bookkeeping and persistence.

Available MCP Session Tools

# Create new session (call FIRST before building)
mcp__agent-builder__create_session(name="Support Ticket Agent")
# Returns: session_id, automatically sets as active session

# Get current session status (use for progress tracking)
status = mcp__agent-builder__get_session_status()
# Returns: {
#   "session_id": "build_20250122_...",
#   "name": "Support Ticket Agent",
#   "has_goal": true,
#   "node_count": 5,
#   "edge_count": 7,
#   "nodes": ["parse-ticket", "categorize", ...],
#   "edges": [("parse-ticket", "categorize"), ...]
# }

# List all saved sessions
mcp__agent-builder__list_sessions()

# Load previous session
mcp__agent-builder__load_session_by_id(session_id="build_...")

# Delete session
mcp__agent-builder__delete_session(session_id="build_...")

How MCP Session Works

The BuildSession class (in core/framework/mcp/agent_builder_server.py) automatically:

Persists to disk after every operation (_save_session() called automatically)
Tracks all components: goal, nodes, edges, mcp_servers
Maintains timestamps: created_at, last_modified
Stores to: ~/.claude-code-agent-builder/sessions/

When you call MCP tools like:

mcp__agent-builder__set_goal(...) - Automatically added to session.goal and saved
mcp__agent-builder__add_node(...) - Automatically added to session.nodes and saved
mcp__agent-builder__add_edge(...) - Automatically added to session.edges and saved

No manual bookkeeping needed - the MCP server handles it all!

MCP Tool Parameter Formats

CRITICAL: All MCP tools that accept complex data require JSON-formatted strings. This is the most common source of errors.

mcpagent-builderset_goal

# CORRECT FORMAT:
mcp__agent-builder__set_goal(
    goal_id="process-support-tickets",
    name="Process Customer Support Tickets",
    description="Automatically process incoming customer support tickets...",
    success_criteria='[{"id": "accurate-categorization", "description": "Correctly classify ticket type", "metric": "classification_accuracy", "target": "90%", "weight": 0.25}, {"id": "response-quality", "description": "Provide helpful response", "metric": "customer_satisfaction", "target": "90%", "weight": 0.30}]',
    constraints='[{"id": "privacy-protection", "description": "Must not expose sensitive data", "constraint_type": "security", "category": "data_privacy"}, {"id": "escalation-threshold", "description": "Escalate when confidence below 70%", "constraint_type": "quality", "category": "accuracy"}]'
)

# WRONG - Using pipe-delimited or custom formats:
success_criteria="id1:desc1:metric1:target1|id2:desc2:metric2:target2"  # ❌ WRONG
constraints="[constraint1, constraint2]"  # ❌ WRONG - not valid JSON

Required fields for success_criteria JSON objects:

id (string): Unique identifier
description (string): What this criterion measures
metric (string): Name of the metric
target (string): Target value (e.g., "90%", "<30")
weight (float): Weight for scoring (0.0-1.0, should sum to 1.0)

Required fields for constraints JSON objects:

id (string): Unique identifier
description (string): What this constraint enforces
constraint_type (string): Type (e.g., "security", "quality", "performance", "functional")
category (string): Category (e.g., "data_privacy", "accuracy", "response_time")

mcpagent-builderadd_node

# CORRECT FORMAT:
mcp__agent-builder__add_node(
    node_id="parse-ticket",
    name="Parse Ticket",
    description="Extract key information from incoming ticket",
    node_type="llm",
    input_keys='["ticket_content", "customer_id"]',  # JSON array of strings
    output_keys='["parsed_data", "category_hint"]',   # JSON array of strings
    system_prompt="You are a ticket parser. Extract: subject, body, sentiment, urgency indicators.",
    tools='[]',  # JSON array of tool names, empty if none
    routes='{}'  # JSON object for routing, empty if none
)

# WRONG formats:
input_keys="ticket_content, customer_id"  # ❌ WRONG - not JSON
input_keys=["ticket_content", "customer_id"]  # ❌ WRONG - Python list, not string
tools="tool1, tool2"  # ❌ WRONG - not JSON array

Node types:

"llm" - LLM-powered node (most common)
"function" - Python function execution
"router" - Conditional routing node
"parallel" - Parallel execution node

mcpagent-builderadd_edge

# CORRECT FORMAT:
mcp__agent-builder__add_edge(
    edge_id="parse-to-categorize",
    source="parse-ticket",
    target="categorize-issue",
    condition="on_success",  # or "always", "on_failure", "conditional"
    condition_expr="",  # Python expression for "conditional" type
    priority=1
)

# For conditional routing:
mcp__agent-builder__add_edge(
    edge_id="confidence-check-high",
    source="check-confidence",
    target="finalize-output",
    condition="conditional",
    condition_expr="context.get('confidence', 0) >= 0.7",
    priority=1
)

Edge conditions:

"always" - Always traverse this edge
"on_success" - Traverse if source node succeeds
"on_failure" - Traverse if source node fails
"conditional" - Traverse if condition_expr evaluates to True

Show Progress to User

# Get session status to show progress
status = json.loads(mcp__agent-builder__get_session_status())

print(f"\n📊 Building Progress:")
print(f"   Session: {status['name']}")
print(f"   Goal defined: {status['has_goal']}")
print(f"   Nodes: {status['node_count']}")
print(f"   Edges: {status['edge_count']}")
print(f"   Nodes added: {', '.join(status['nodes'])}")

Benefits:

Automatic persistence - survive crashes/restarts
Clear audit trail - all operations logged
Session resume - continue from where you left off
Progress tracking built-in
No manual state management needed

Step-by-Step Guide

Step 1: Create Building Session & Package Structure

When user requests an agent, immediately register tools, create MCP session, and package:

# 0. MANDATORY FIRST: Register hive-tools MCP server
# cwd path is relative to project root (where you run Claude Code from)
mcp__agent-builder__add_mcp_server(
    name="hive-tools",
    transport="stdio",
    command="python",
    args='["mcp_server.py", "--stdio"]',
    cwd="tools",  # Relative to project root
    description="Hive tools MCP server"
)
print("✅ Registered hive-tools MCP server")

# 1. Create MCP building session
agent_name = "technical_research_agent"  # snake_case
session_result = mcp__agent-builder__create_session(name=agent_name.replace('_', ' ').title())
session_id = json.loads(session_result)["session_id"]
print(f"✅ Created building session: {session_id}")

# 1. Create directory
package_path = f"exports/{agent_name}"

Bash(f"mkdir -p {package_path}/nodes")

# 2. Write skeleton files
Write(
    file_path=f"{package_path}/__init__.py",
    content='''"""
Agent package - will be populated as build progresses.
"""
'''
)

Write(
    file_path=f"{package_path}/nodes/__init__.py",
    content='''"""Node definitions."""
from framework.graph import NodeSpec

# Nodes will be added here as they are approved

__all__ = []
'''
)

Write(
    file_path=f"{package_path}/agent.py",
    content='''"""Agent graph construction."""
from framework.graph import EdgeSpec, EdgeCondition, Goal, SuccessCriterion, Constraint
from framework.graph.edge import GraphSpec
from framework.graph.executor import ExecutionResult
from framework.runtime.agent_runtime import AgentRuntime, create_agent_runtime
from framework.runtime.execution_stream import EntryPointSpec
from framework.llm import LiteLLMProvider
from framework.runner.tool_registry import ToolRegistry

# Goal will be added when defined
# Nodes will be imported from .nodes
# Edges will be added when approved
# Agent class will be created when graph is complete
'''
)

Write(
    file_path=f"{package_path}/config.py",
    content='''"""Runtime configuration."""
from dataclasses import dataclass

@dataclass
class RuntimeConfig:
    model: str = "cerebras/zai-glm-4.7"
    temperature: float = 0.7
    max_tokens: int = 4096

default_config = RuntimeConfig()

# Metadata will be added when goal is set
'''
)

Write(
    file_path=f"{package_path}/__main__.py",
    content=CLI_TEMPLATE  # Full CLI template (see below)
)

Show user:

✅ Package created: exports/technical_research_agent/
📁 Files created:
   - __init__.py (skeleton)
   - __main__.py (CLI ready)
   - agent.py (skeleton)
   - nodes/__init__.py (empty)
   - config.py (skeleton)

You can open these files now and watch them grow as we build!

Step 2: Define Goal

Propose goal, get approval, write immediately:

# After user approves goal...

goal_code = f'''
goal = Goal(
    id="{goal_id}",
    name="{name}",
    description="{description}",
    success_criteria=[
        SuccessCriterion(
            id="{sc.id}",
            description="{sc.description}",
            metric="{sc.metric}",
            target="{sc.target}",
            weight={sc.weight},
        ),
        # 3-5 success criteria total
    ],
    constraints=[
        Constraint(
            id="{c.id}",
            description="{c.description}",
            constraint_type="{c.constraint_type}",
            category="{c.category}",
        ),
        # 1-5 constraints total
    ],
)
'''

# Append to agent.py
Read(f"{package_path}/agent.py")  # Must read first
Edit(
    file_path=f"{package_path}/agent.py",
    old_string="# Goal will be added when defined",
    new_string=f"# Goal definition\n{goal_code}"
)

# Write metadata to config.py
metadata_code = f'''
@dataclass
class AgentMetadata:
    name: str = "{name}"
    version: str = "1.0.0"
    description: str = "{description}"

metadata = AgentMetadata()
'''

Read(f"{package_path}/config.py")
Edit(
    file_path=f"{package_path}/config.py",
    old_string="# Metadata will be added when goal is set",
    new_string=f"# Agent metadata\n{metadata_code}"
)

Show user:

✅ Goal written to agent.py
✅ Metadata written to config.py

Open exports/technical_research_agent/agent.py to see the goal!

Note: Goal is automatically tracked in MCP session. Use mcp__agent-builder__get_session_status() to check progress.

Step 3: Add Nodes (Incremental)

⚠️ CRITICAL: TOOL DISCOVERY BEFORE NODE CREATION

# MANDATORY FIRST STEP - Run this BEFORE creating any nodes!
print("🔍 Discovering available tools...")
available_tools = mcp__agent-builder__list_mcp_tools()
print(f"Available tools: {available_tools}")

# Store for reference when adding nodes
# Example output: ["web_search", "web_scrape", "write_to_file"]

Before adding any node with tools:

ALREADY DONE: Discovered available tools above
Verify each tool you want to use exists in the list
If a tool doesn't exist, inform the user and ask how to proceed
Choose correct node_type:
- llm_generate - NO tools, pure LLM output
- llm_tool_use - MUST use tools from the available list

After writing each node: 5. MANDATORY: Validate with mcp__agent-builder__test_node() before proceeding 6. MANDATORY: Check MCP session status to track progress 7. Only proceed to next node after validation passes

Reference the online_research_agent example in examples/online_research_agent/ for correct patterns.

For each node, write immediately after approval:

# After user approves node...

node_code = f'''
{node_id.replace('-', '_')}_node = NodeSpec(
    id="{node_id}",
    name="{name}",
    description="{description}",
    node_type="{node_type}",
    input_keys={input_keys},
    output_keys={output_keys},
    system_prompt="""\\
{system_prompt}
""",
    tools={tools},
    max_retries={max_retries},

    # OPTIONAL: Add schemas for OutputCleaner validation (recommended for critical paths)
    # input_schema={{
    #     "field_name": {{"type": "string", "required": True, "description": "Field description"}},
    # }},
    # output_schema={{
    #     "result": {{"type": "dict", "required": True, "description": "Analysis result"}},
    # }},
)

'''

# Append to nodes/__init__.py
Read(f"{package_path}/nodes/__init__.py")
Edit(
    file_path=f"{package_path}/nodes/__init__.py",
    old_string="__all__ = []",
    new_string=f"{node_code}\n__all__ = []"
)

# Update __all__ exports
all_node_names = [n.replace('-', '_') + '_node' for n in approved_nodes]
all_exports = f"__all__ = {all_node_names}"

Edit(
    file_path=f"{package_path}/nodes/__init__.py",
    old_string="__all__ = []",
    new_string=all_exports
)

Show user after each node:

✅ Added analyze_request_node to nodes/__init__.py
📊 Progress: 1/6 nodes added

Open exports/technical_research_agent/nodes/__init__.py to see it!

Repeat for each node. User watches the file grow.

MANDATORY: Validate Each Node with MCP Tools

After writing EVERY node, you MUST validate before proceeding:

# Node is already written to file. Now VALIDATE IT (REQUIRED):
validation_result = json.loads(mcp__agent-builder__test_node(
    node_id="analyze-request",
    test_input='{"query": "test query"}',
    mock_llm_response='{"analysis": "mock output"}'
))

# Check validation result
if validation_result["valid"]:
    # Show user validation passed
    print(f"✅ Node validation passed: analyze-request")

    # Show session progress
    status = json.loads(mcp__agent-builder__get_session_status())
    print(f"📊 Session progress: {status['node_count']} nodes added")
else:
    # STOP - Do not proceed until fixed
    print(f"❌ Node validation FAILED:")
    for error in validation_result["errors"]:
        print(f"   - {error}")
    print("⚠️ Must fix node before proceeding to next component")
    # Ask user how to proceed

CRITICAL: Do NOT proceed to the next node until validation passes. Bugs caught here prevent wasted work later.

Step 4: Connect Edges

After all nodes approved, add edges:

# Generate edges code
edges_code = "edges = [\n"
for edge in approved_edges:
    edges_code += f'''    EdgeSpec(
        id="{edge.id}",
        source="{edge.source}",
        target="{edge.target}",
        condition=EdgeCondition.{edge.condition.upper()},
'''
    if edge.condition_expr:
        edges_code += f'        condition_expr="{edge.condition_expr}",\n'
    edges_code += f'        priority={edge.priority},\n'
    edges_code += '    ),\n'
edges_code += "]\n"

# Write to agent.py
Read(f"{package_path}/agent.py")
Edit(
    file_path=f"{package_path}/agent.py",
    old_string="# Edges will be added when approved",
    new_string=f"# Edge definitions\n{edges_code}"
)

# Write entry points and terminal nodes
# ⚠️ CRITICAL: entry_points format must be {"start": "node_id"}
# Common mistake: {"node_id": ["input_keys"]} is WRONG
# Correct format: {"start": "first-node-id"}
# Reference: See exports/outbound_sales_agent/agent.py for example

graph_config = f'''
# Graph configuration
entry_node = "{entry_node_id}"
entry_points = {{"start": "{entry_node_id}"}}  # CRITICAL: Must be {{"start": "node-id"}}
pause_nodes = {pause_nodes}
terminal_nodes = {terminal_nodes}

# Collect all nodes
nodes = [
    {', '.join(node_names)},
]
'''

Edit(
    file_path=f"{package_path}/agent.py",
    old_string="# Agent class will be created when graph is complete",
    new_string=graph_config
)

Show user:

✅ Edges written to agent.py
✅ Graph configuration added

5 edges connecting 6 nodes

MANDATORY: Validate Graph Structure

After writing edges, you MUST validate before proceeding to finalization:

# Edges already written to agent.py. Now VALIDATE STRUCTURE (REQUIRED):
graph_validation = json.loads(mcp__agent-builder__validate_graph())

# Check for structural issues
if graph_validation["valid"]:
    print("✅ Graph structure validated successfully")

    # Show session summary
    status = json.loads(mcp__agent-builder__get_session_status())
    print(f"   - Nodes: {status['node_count']}")
    print(f"   - Edges: {status['edge_count']}")
    print(f"   - Entry point: {entry_node_id}")
else:
    print("❌ Graph validation FAILED:")
    for error in graph_validation["errors"]:
        print(f"   ERROR: {error}")
    print("\n⚠️ Must fix graph structure before finalizing agent")
    # Ask user how to proceed

# Additional validation: Check entry_points format
if not isinstance(entry_points, dict):
    print("❌ CRITICAL ERROR: entry_points must be a dict")
    print(f"   Current value: {entry_points} (type: {type(entry_points)})")
    print("   Correct format: {'start': 'node-id'}")
    # STOP - This is the mistake that caused the support_ticket_agent bug

if entry_points.get("start") != entry_node_id:
    print("❌ CRITICAL ERROR: entry_points['start'] must match entry_node")
    print(f"   entry_points: {entry_points}")
    print(f"   entry_node: {entry_node_id}")
    print("   They must be consistent!")

CRITICAL: Do NOT proceed to Step 5 (finalization) until graph validation passes. This checkpoint prevents structural bugs from reaching production.

Step 5: Finalize Agent Class

Pre-flight checks before finalization:

# MANDATORY: Verify all validations passed before finalizing
print("\n🔍 Pre-finalization Checklist:")

# Get current session status
status = json.loads(mcp__agent-builder__get_session_status())

checks_passed = True

# Check 1: Goal defined
if not status["has_goal"]:
    print("❌ No goal defined")
    checks_passed = False
else:
    print(f"✅ Goal defined: {status['goal_name']}")

# Check 2: Nodes added
if status["node_count"] == 0:
    print("❌ No nodes added")
    checks_passed = False
else:
    print(f"✅ {status['node_count']} nodes added: {', '.join(status['nodes'])}")

# Check 3: Edges added
if status["edge_count"] == 0:
    print("❌ No edges added")
    checks_passed = False
else:
    print(f"✅ {status['edge_count']} edges added")

# Check 4: Entry points format correct
if not isinstance(entry_points, dict) or "start" not in entry_points:
    print("❌ CRITICAL: entry_points format incorrect")
    print(f"   Current: {entry_points}")
    print("   Required: {'start': 'node-id'}")
    checks_passed = False
else:
    print(f"✅ Entry points valid: {entry_points}")

if not checks_passed:
    print("\n⚠️ CANNOT PROCEED to finalization until all checks pass")
    print("   Fix the issues above first")
    # Ask user how to proceed or stop here
    return

print("\n✅ All pre-flight checks passed - proceeding to finalization\n")

Write the agent class using AgentRuntime (supports multi-entrypoint, HITL pause/resume):

agent_class_code = f'''

class {agent_class_name}:
    """
    {agent_description}

    Uses AgentRuntime for multi-entrypoint support with HITL pause/resume.
    """

    def __init__(self, config=None):
        self.config = config or default_config
        self.goal = goal
        self.nodes = nodes
        self.edges = edges
        self.entry_node = entry_node
        self.entry_points = entry_points
        self.pause_nodes = pause_nodes
        self.terminal_nodes = terminal_nodes
        self._runtime: AgentRuntime | None = None
        self._graph: GraphSpec | None = None

    def _build_entry_point_specs(self) -> list[EntryPointSpec]:
        """Convert entry_points dict to EntryPointSpec list."""
        specs = []
        for ep_id, node_id in self.entry_points.items():
            if ep_id == "start":
                trigger_type = "manual"
                name = "Start"
            elif "_resume" in ep_id:
                trigger_type = "resume"
                name = f"Resume from {{ep_id.replace('_resume', '')}}"
            else:
                trigger_type = "manual"
                name = ep_id.replace("-", " ").title()

            specs.append(EntryPointSpec(
                id=ep_id,
                name=name,
                entry_node=node_id,
                trigger_type=trigger_type,
                isolation_level="shared",
            ))
        return specs

    def _create_runtime(self, mock_mode=False) -> AgentRuntime:
        """Create AgentRuntime instance."""
        import json
        from pathlib import Path

        # Persistent storage in ~/.hive for telemetry and run history
        storage_path = Path.home() / ".hive" / "{agent_name}"
        storage_path.mkdir(parents=True, exist_ok=True)

        tool_registry = ToolRegistry()

        # Load MCP servers if not in mock mode
        if not mock_mode:
            agent_dir = Path(__file__).parent
            mcp_config_path = agent_dir / "mcp_servers.json"

            if mcp_config_path.exists():
                with open(mcp_config_path) as f:
                    mcp_servers = json.load(f)

                for server_name, server_config in mcp_servers.items():
                    server_config["name"] = server_name
                    # Resolve relative cwd paths
                    if "cwd" in server_config and not Path(server_config["cwd"]).is_absolute():
                        server_config["cwd"] = str(agent_dir / server_config["cwd"])
                    tool_registry.register_mcp_server(server_config)

        llm = None
        if not mock_mode:
            # LiteLLMProvider uses environment variables for API keys
            llm = LiteLLMProvider(model=self.config.model)

        self._graph = GraphSpec(
            id="{agent_name}-graph",
            goal_id=self.goal.id,
            version="1.0.0",
            entry_node=self.entry_node,
            entry_points=self.entry_points,
            terminal_nodes=self.terminal_nodes,
            pause_nodes=self.pause_nodes,
            nodes=self.nodes,
            edges=self.edges,
            default_model=self.config.model,
            max_tokens=self.config.max_tokens,
        )

        # Create AgentRuntime with all entry points
        self._runtime = create_agent_runtime(
            graph=self._graph,
            goal=self.goal,
            storage_path=storage_path,
            entry_points=self._build_entry_point_specs(),
            llm=llm,
            tools=list(tool_registry.get_tools().values()),
            tool_executor=tool_registry.get_executor(),
        )

        return self._runtime

    async def start(self, mock_mode=False) -> None:
        """Start the agent runtime."""
        if self._runtime is None:
            self._create_runtime(mock_mode=mock_mode)
        await self._runtime.start()

    async def stop(self) -> None:
        """Stop the agent runtime."""
        if self._runtime is not None:
            await self._runtime.stop()

    async def trigger(
        self,
        entry_point: str,
        input_data: dict,
        correlation_id: str | None = None,
        session_state: dict | None = None,
    ) -> str:
        """
        Trigger execution at a specific entry point (non-blocking).

        Args:
            entry_point: Entry point ID (e.g., "start", "pause-node_resume")
            input_data: Input data for the execution
            correlation_id: Optional ID to correlate related executions
            session_state: Optional session state to resume from (with paused_at, memory)

        Returns:
            Execution ID for tracking
        """
        if self._runtime is None or not self._runtime.is_running:
            raise RuntimeError("Agent runtime not started. Call start() first.")
        return await self._runtime.trigger(entry_point, input_data, correlation_id, session_state=session_state)

    async def trigger_and_wait(
        self,
        entry_point: str,
        input_data: dict,
        timeout: float | None = None,
        session_state: dict | None = None,
    ) -> ExecutionResult | None:
        """
        Trigger execution and wait for completion.

        Args:
            entry_point: Entry point ID
            input_data: Input data for the execution
            timeout: Maximum time to wait (seconds)
            session_state: Optional session state to resume from (with paused_at, memory)

        Returns:
            ExecutionResult or None if timeout
        """
        if self._runtime is None or not self._runtime.is_running:
            raise RuntimeError("Agent runtime not started. Call start() first.")
        return await self._runtime.trigger_and_wait(entry_point, input_data, timeout, session_state=session_state)

    async def run(self, context: dict, mock_mode=False, session_state=None) -> ExecutionResult:
        """
        Run the agent (convenience method for simple single execution).

        For more control, use start() + trigger_and_wait() + stop().
        """
        await self.start(mock_mode=mock_mode)
        try:
            # Determine entry point based on session_state
            if session_state and "paused_at" in session_state:
                paused_node = session_state["paused_at"]
                resume_key = f"{{paused_node}}_resume"
                if resume_key in self.entry_points:
                    entry_point = resume_key
                else:
                    entry_point = "start"
            else:
                entry_point = "start"

            result = await self.trigger_and_wait(entry_point, context, session_state=session_state)
            return result or ExecutionResult(success=False, error="Execution timeout")
        finally:
            await self.stop()

    async def get_goal_progress(self) -> dict:
        """Get goal progress across all executions."""
        if self._runtime is None:
            raise RuntimeError("Agent runtime not started")
        return await self._runtime.get_goal_progress()

    def get_stats(self) -> dict:
        """Get runtime statistics."""
        if self._runtime is None:
            return {{"running": False}}
        return self._runtime.get_stats()

    def info(self):
        """Get agent information."""
        return {{
            "name": metadata.name,
            "version": metadata.version,
            "description": metadata.description,
            "goal": {{
                "name": self.goal.name,
                "description": self.goal.description,
            }},
            "nodes": [n.id for n in self.nodes],
            "edges": [e.id for e in self.edges],
            "entry_node": self.entry_node,
            "entry_points": self.entry_points,
            "pause_nodes": self.pause_nodes,
            "terminal_nodes": self.terminal_nodes,
            "multi_entrypoint": True,
        }}

    def validate(self):
        """Validate agent structure."""
        errors = []
        warnings = []

        node_ids = {{node.id for node in self.nodes}}
        for edge in self.edges:
            if edge.source not in node_ids:
                errors.append(f"Edge {{edge.id}}: source '{{edge.source}}' not found")
            if edge.target not in node_ids:
                errors.append(f"Edge {{edge.id}}: target '{{edge.target}}' not found")

        if self.entry_node not in node_ids:
            errors.append(f"Entry node '{{self.entry_node}}' not found")

        for terminal in self.terminal_nodes:
            if terminal not in node_ids:
                errors.append(f"Terminal node '{{terminal}}' not found")

        for pause in self.pause_nodes:
            if pause not in node_ids:
                errors.append(f"Pause node '{{pause}}' not found")

        # Validate entry points
        for ep_id, node_id in self.entry_points.items():
            if node_id not in node_ids:
                errors.append(f"Entry point '{{ep_id}}' references unknown node '{{node_id}}'")

        return {{
            "valid": len(errors) == 0,
            "errors": errors,
            "warnings": warnings,
        }}


# Create default instance
default_agent = {agent_class_name}()
'''

# Append agent class
Read(f"{package_path}/agent.py")
Edit(
    file_path=f"{package_path}/agent.py",
    old_string="nodes = [",
    new_string=f"nodes = [\n{agent_class_code}"
)

# Finalize __init__.py exports
init_content = f'''"""
{agent_description}
"""

from .agent import {agent_class_name}, default_agent, goal, nodes, edges
from .config import RuntimeConfig, AgentMetadata, default_config, metadata

__version__ = "1.0.0"

__all__ = [
    "{agent_class_name}",
    "default_agent",
    "goal",
    "nodes",
    "edges",
    "RuntimeConfig",
    "AgentMetadata",
    "default_config",
    "metadata",
]
'''

Read(f"{package_path}/__init__.py")
Edit(
    file_path=f"{package_path}/__init__.py",
    old_string='"""',
    new_string=init_content,
    replace_all=True
)

# Write README
readme_content = f'''# {agent_name.replace('_', ' ').title()}

{agent_description}

## Usage

```bash
# Show agent info
python -m {agent_name} info

# Validate structure
python -m {agent_name} validate

# Run agent
python -m {agent_name} run --input '{{"key": "value"}}'

# Interactive shell
python -m {agent_name} shell

As Python Module

from {agent_name} import default_agent

result = await default_agent.run({{"key": "value"}})

Structure

agent.py - Goal, edges, graph construction
nodes/__init__.py - Node definitions
config.py - Runtime configuration
__main__.py - CLI interface '''

Write( file_path=f"{package_path}/README.md", content=readme_content )


**Show user:**

✅ Agent class written to agent.py ✅ Package exports finalized in init.py ✅ README.md generated

🎉 Agent complete: exports/technical_research_agent/

Commands: python -m technical_research_agent info python -m technical_research_agent validate python -m technical_research_agent run --input '{"topic": "..."}'


**Final session summary:**

```python
# Show final MCP session status
status = json.loads(mcp__agent-builder__get_session_status())

print("\n📊 Build Session Summary:")
print(f"   Session ID: {status['session_id']}")
print(f"   Agent: {status['name']}")
print(f"   Goal: {status['goal_name']}")
print(f"   Nodes: {status['node_count']}")
print(f"   Edges: {status['edge_count']}")
print(f"   MCP Servers: {status['mcp_servers_count']}")
print("\n✅ Agent construction complete with full validation")
print(f"\nSession saved to: ~/.claude-code-agent-builder/sessions/{status['session_id']}.json")

CLI Template

CLI_TEMPLATE = '''"""
CLI entry point for agent.

Uses AgentRuntime for multi-entrypoint support with HITL pause/resume.
"""

import asyncio
import json
import logging
import sys
import click

from .agent import default_agent, {agent_class_name}


def setup_logging(verbose=False, debug=False):
    """Configure logging for execution visibility."""
    if debug:
        level, fmt = logging.DEBUG, "%(asctime)s %(name)s: %(message)s"
    elif verbose:
        level, fmt = logging.INFO, "%(message)s"
    else:
        level, fmt = logging.WARNING, "%(levelname)s: %(message)s"
    logging.basicConfig(level=level, format=fmt, stream=sys.stderr)
    logging.getLogger("framework").setLevel(level)


@click.group()
@click.version_option(version="1.0.0")
def cli():
    """Agent CLI."""
    pass


@cli.command()
@click.option("--input", "-i", "input_json", type=str, required=True)
@click.option("--mock", is_flag=True, help="Run in mock mode")
@click.option("--quiet", "-q", is_flag=True, help="Only output result JSON")
@click.option("--verbose", "-v", is_flag=True, help="Show execution details")
@click.option("--debug", is_flag=True, help="Show debug logging")
@click.option("--session", "-s", type=str, help="Session ID to resume from pause")
def run(input_json, mock, quiet, verbose, debug, session):
    """Execute the agent."""
    if not quiet:
        setup_logging(verbose=verbose, debug=debug)

    try:
        context = json.loads(input_json)
    except json.JSONDecodeError as e:
        click.echo(f"Error parsing input JSON: {e}", err=True)
        sys.exit(1)

    # Load session state if resuming
    session_state = None
    if session:
        # TODO: Load session state from storage
        pass

    result = asyncio.run(default_agent.run(context, mock_mode=mock, session_state=session_state))

    output_data = {
        "success": result.success,
        "steps_executed": result.steps_executed,
        "output": result.output,
    }
    if result.error:
        output_data["error"] = result.error
    if result.paused_at:
        output_data["paused_at"] = result.paused_at
        output_data["message"] = "Agent paused for user input. Use --session flag to resume."

    click.echo(json.dumps(output_data, indent=2, default=str))
    sys.exit(0 if result.success else 1)


@cli.command()
@click.option("--json", "output_json", is_flag=True)
def info(output_json):
    """Show agent information."""
    info_data = default_agent.info()
    if output_json:
        click.echo(json.dumps(info_data, indent=2))
    else:
        click.echo(f"Agent: {info_data['name']}")
        click.echo(f"Nodes: {', '.join(info_data['nodes'])}")
        click.echo(f"Entry: {info_data['entry_node']}")
        if info_data.get('pause_nodes'):
            click.echo(f"Pause nodes: {', '.join(info_data['pause_nodes'])}")


@cli.command()
def validate():
    """Validate agent structure."""
    validation = default_agent.validate()
    if validation["valid"]:
        click.echo("✓ Agent is valid")
    else:
        click.echo("✗ Agent has errors:")
        for error in validation["errors"]:
            click.echo(f"  ERROR: {error}")
    sys.exit(0 if validation["valid"] else 1)


@cli.command()
@click.option("--verbose", "-v", is_flag=True)
def shell(verbose):
    """Interactive agent session with HITL support."""
    asyncio.run(_interactive_shell(verbose))


async def _interactive_shell(verbose=False):
    """Async interactive shell - keeps runtime alive across requests."""
    setup_logging(verbose=verbose)

    click.echo("=== Agent Interactive Mode ===")
    click.echo("Enter your input (or 'quit' to exit):\\n")

    agent = {agent_class_name}()
    await agent.start()

    session_state = None

    try:
        while True:
            try:
                user_input = await asyncio.get_event_loop().run_in_executor(None, input, "> ")
                if user_input.lower() in ['quit', 'exit', 'q']:
                    click.echo("Goodbye!")
                    break

                if not user_input.strip():
                    continue

                # Determine entry point and context based on session state
                resume_session = None
                if session_state and "paused_at" in session_state:
                    paused_node = session_state["paused_at"]
                    resume_key = f"{{paused_node}}_resume"
                    if resume_key in agent.entry_points:
                        entry_point = resume_key
                        # New input data (session_state is passed separately)
                        context = {{"user_response": user_input}}
                        resume_session = session_state
                    else:
                        entry_point = "start"
                        context = {{"user_message": user_input}}
                    click.echo("\\n⏳ Processing your response...")
                else:
                    entry_point = "start"
                    context = {{"user_message": user_input}}
                    click.echo("\\n⏳ Thinking...")

                result = await agent.trigger_and_wait(entry_point, context, session_state=resume_session)

                if result is None:
                    click.echo("\\n[Execution timed out]\\n")
                    session_state = None
                    continue

                # Extract user-facing message
                message = result.output.get("final_response", "") or result.output.get("response", "")
                if not message and result.output:
                    message = json.dumps(result.output, indent=2)

                click.echo(f"\\n{{message}}\\n")

                if result.paused_at:
                    click.echo(f"[Paused - waiting for your response]")
                    session_state = result.session_state
                else:
                    session_state = None

            except KeyboardInterrupt:
                click.echo("\\nGoodbye!")
                break
            except Exception as e:
                click.echo(f"Error: {{e}}", err=True)
                import traceback
                traceback.print_exc()
    finally:
        await agent.stop()


if __name__ == "__main__":
    cli()
'''

Testing During Build

After nodes are added:

# Test individual node
python -c "
from exports.my_agent.nodes import analyze_request_node
print(analyze_request_node.id)
print(analyze_request_node.input_keys)
"

# Validate current state
PYTHONPATH=core:exports python -m my_agent validate

# Show info
PYTHONPATH=core:exports python -m my_agent info

Approval Pattern

Use AskUserQuestion for all approvals:

response = AskUserQuestion(
    questions=[{
        "question": "Do you approve this [component]?",
        "header": "Approve",
        "options": [
            {
                "label": "✓ Approve (Recommended)",
                "description": "Component looks good, proceed"
            },
            {
                "label": "✗ Reject & Modify",
                "description": "Need to make changes"
            },
            {
                "label": "⏸ Pause & Review",
                "description": "Need more time to review"
            }
        ],
        "multiSelect": false
    }]
)

Framework Features

OutputCleaner - Automatic I/O Validation and Cleaning

NEW FEATURE: The framework automatically validates and cleans node outputs between edges using a fast LLM (Cerebras llama-3.3-70b).

What it does:

✅ Validates output matches next node's input schema
✅ Detects JSON parsing trap (entire response in one key)
✅ Cleans malformed output automatically (~200-500ms, ~$0.001 per cleaning)
✅ Boosts success rates by 1.8-2.2x
✅ Enabled by default - no code changes needed!

How to leverage it:

Add input_schema and output_schema to critical nodes for better validation:

critical_node = NodeSpec(
    id="approval-decision",
    name="Approval Decision",
    node_type="llm_generate",
    input_keys=["analysis", "risk_score"],
    output_keys=["decision", "reason"],

    # Schemas enable OutputCleaner to validate and clean better
    input_schema={
        "analysis": {
            "type": "dict",
            "required": True,
            "description": "Contract analysis with findings"
        },
        "risk_score": {
            "type": "number",
            "required": True,
            "description": "Risk score 0-10"
        },
    },
    output_schema={
        "decision": {
            "type": "string",
            "required": True,
            "description": "Approval decision: APPROVED, REJECTED, or ESCALATE"
        },
        "reason": {
            "type": "string",
            "required": True,
            "description": "Justification for the decision"
        },
    },

    system_prompt="""...""",
)

Supported schema types:

"string" or "str" - String values
"int" or "integer" - Integer numbers
"float" - Float numbers
"number" - Int or float
"bool" or "boolean" - Boolean values
"dict" or "object" - Dictionary/object
"list" or "array" - List/array
"any" - Any type (no validation)

When to add schemas:

✅ Critical paths where failure cascades
✅ Expensive nodes where retry is costly
✅ Nodes with strict output requirements
✅ Nodes that frequently produce malformed output

When to skip schemas:

❌ Simple pass-through nodes
❌ Terminal nodes (no next node to affect)
❌ Fast local operations
❌ Nodes with robust error handling

Monitoring: Check logs for cleaning events:

⚠ Output validation failed for analyze → recommend: 1 error(s)
🧹 Cleaning output from 'analyze' using cerebras/llama-3.3-70b
✓ Output cleaned successfully

If you see frequent cleanings on the same edge:

Review the source node's system prompt
Add explicit JSON formatting instructions
Consider improving output structure

System Prompt Best Practices

For nodes with multiple output_keys, ALWAYS enforce JSON:

system_prompt="""You are a contract analyzer.

CRITICAL: Return ONLY raw JSON. NO markdown, NO code blocks, NO ```json```.
Just the JSON object starting with { and ending with }.

Return ONLY this JSON structure:
{
  "analysis": {...},
  "risk_score": 7.5,
  "compliance_issues": [...]
}

Do NOT include any explanatory text before or after the JSON.
"""

Why this matters:

LLMs often wrap JSON in markdown (```json\n{...}\n```)
LLMs add explanations before/after JSON
Without explicit instructions, output may be malformed
OutputCleaner can fix these, but better to prevent them

Next Steps

After completing construction:

If agent structure complete:

Validate: python -m agent_name validate
Test basic execution: python -m agent_name info
Proceed to testing-agent skill for comprehensive tests

If implementation needed:

Check for STATUS.md or IMPLEMENTATION_GUIDE.md in agent directory
May need Python functions or MCP tool integration

Related Skills

building-agents-core - Fundamental concepts
building-agents-patterns - Best practices and examples
testing-agent - Test and validate completed agents
agent-workflow - Complete workflow orchestrator

About

Building Agents - Construction Process

Reference Example: Online Research Agent

CRITICAL: Register hive-tools MCP Server FIRST

CRITICAL: Discover Available Tools

CRITICAL: entry_points Format Reference

Correct Format

WRONG Formats (DO NOT USE)

Validation Check

AgentRuntime Architecture

Key Components

Entry Point Specs

HITL Pause/Resume Pattern

LLM Provider Configuration

Environment Setup

Model Configuration

Supported Providers via LiteLLM

Building Session Management with MCP

Available MCP Session Tools

How MCP Session Works

MCP Tool Parameter Formats

mcpagent-builderset_goal

mcpagent-builderadd_node

mcpagent-builderadd_edge

Show Progress to User

Step-by-Step Guide

Step 1: Create Building Session & Package Structure

Step 2: Define Goal

Step 3: Add Nodes (Incremental)

MANDATORY: Validate Each Node with MCP Tools

Step 4: Connect Edges

MANDATORY: Validate Graph Structure

Step 5: Finalize Agent Class

As Python Module

Structure

CLI Template

Testing During Build

Approval Pattern

Framework Features

OutputCleaner - Automatic I/O Validation and Cleaning

System Prompt Best Practices

Next Steps

Related Skills

Use it

Manifest

Reviews