THE TOOL REGISTRY

CHAPTER SUMMARY The tool registry is the harness's catalog of tools, storing names, descriptions, schemas, permissions, handlers, and production fields like versions and rate limits. Dispatch looks up a requested tool, validates inputs, checks permissions, applies limits, runs the handler, and logs the result. Typed handlers share checks within a category so one fix improves many tools. On-demand discovery loads only needed tools to save context and improve tool choice. Versioning and deprecation let tools evolve without breaking existing users. KEY TERMS REVIEW Tool registry: the catalog of available tools. Handler: the code that runs when a tool is called. Dispatch: routing a request to the right code. Typed handler: a category base with shared checks. Context window: the limited amount of text a model can read at once. Token: a small chunk of text, roughly three-quarters of a word. On-demand tool discovery: loading tools only when needed. Versioning: labeling forms of a tool to track changes. Deprecation: marking something outdated and scheduled for removal.