Tool Registry
The catalog of tools an agent is allowed to use, each with a description of what it does and how to call it.
Think of it like
A restaurant menu — the agent can only order what’s printed, and each item comes with a description.
Example
The registry lists send_email, search_web, and query_database, so the agent knows those three exist and exactly what arguments each one takes.
How it actually works
The registry is both a menu and a fence: it tells the agent what’s available and, by omission, what isn’t. Descriptions matter enormously — a vague tool description means the agent picks the wrong tool or mangles the arguments. As registries grow past a few dozen tools, the model starts to struggle to choose, which is why big toolsets get grouped or filtered before they reach the prompt.
For product teams
What’s in the registry defines what your agent can and can’t do — it’s a product decision, not just plumbing.
For engineers
A lookup of available tools with their schemas and descriptions, injected into or filtered before the model context.
Related
- Tool Schema — Each entry is defined by its schema.
- Capability Discovery — How an agent finds out what’s on the menu.
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