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Advanced Tool Use (BM25 Tool Retrieval)

Automatically discover relevant tools at runtime using BM25 lexical search. When you have many tools, this feature keeps the model prompt small: the model sees tools_retriever, searches the runtime tool catalog, then calls the matching tool returned by the search.

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Quick Setup

agent_config = {
    "enable_advanced_tool_use": True  # Enable BM25 retrieval
}

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How It Works

  1. Local tools, MCP tools, workspace/artifact tools, skills, and other registered runtime tools are indexed in memory.
  2. Always-visible harness tools such as tools_retriever, workspace tools, artifact tools, and subagent tools stay directly visible.
  3. The model calls tools_retriever with a semantic query for the capability it needs.
  4. The retriever returns the top matching tools with names, descriptions, and parameters.
  5. The model calls the selected tool normally.

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Benefits

  • Scales to 1000+ tools — searchable tools do not all need to be stuffed into the prompt
  • Zero network I/O — index lives in memory
  • Deterministic — same query always selects same tools
  • Container-friendly — no external dependencies
Enable when you have many local or MCP tools and want the agent to discover the right capability through the runtime tool catalog.