MCP Tool Discovery at Scale

Large catalogs create two problems: discovery overhead and model decision overload.

Protocol-side controls

Use pagination, deterministic ordering, and cache hints. Stable catalogs are especially valuable for upstream prompt caching.

Application-side controls

Organize servers by domain, namespace tools, and filter according to agent responsibility and caller permission.

Do not send every tool to every model turn

The host can maintain a much larger capability inventory than one agent invocation should see.