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Custom Tool

Define a function the LLM can call during reasoning (function-calling style). Great for lookups, calculations, or controlled actions.

When to use

  • The model needs grounded data (DB/search/lookup) or deterministic logic.
  • You want tight control over inputs, side-effects, and format.
  • You prefer the LLM to ask for the tool only when needed.

What it does

  • Declares a callable tool (name, description, arguments, returns).
  • Executes your logic when the Model Node invokes it.
  • Emits a JSON result on output that other nodes can read.

If you already have an HTTP service, use REST API Node with Is Tool to expose it as a tool.

  1. Name: Custom Tool: Something
  2. Description (imperative + when to use):
  3. Code: The actual tool code