TradingAgents/docs/agent/decisions/004-inline-tool-execution.md

type	status	date	agent_author	tags	related_files
decision	active	2026-03-17	claude	agents tools langgraph scanner	tradingagents/agents/utils/tool_runner.py

Context

The existing trading graph uses separate ToolNode graph nodes for tool execution (agent -> tool_node -> agent routing loop). Scanner agents are simpler single-pass nodes — no ToolNode in the graph. When the LLM returned tool_calls, nobody executed them, resulting in empty reports.

The Decision

Created tradingagents/agents/utils/tool_runner.py with run_tool_loop() that runs an inline tool execution loop within each scanner agent node:

1. Invoke chain
2. If tool_calls present -> execute tools -> append ToolMessages -> re-invoke
3. Repeat up to MAX_TOOL_ROUNDS=5 until LLM produces text response

Alternative considered: Adding ToolNode + conditional routing to scanner_setup.py (like trading graph). Rejected — too complex for the fan-out/fan-in pattern.

Constraints

• Trading graph: uses ToolNode in graph (do not change).
• Scanner agents: use run_tool_loop() inline.

Actionable Rules

• When an LLM has bind_tools, there MUST be a tool execution mechanism — either graph-level ToolNode or inline run_tool_loop().
• Always verify the tool execution path exists before marking an agent as complete.