MCP Tool Discovery and Call
How does an MCP client discover a server and call one of its tools?
An agent discovers this server from the AI Catalog, reads its Server Card, asks what it can do with server/discover, lists tools, and calls one. Revision 2026-07-28 has no handshake: every request stands alone and carries its own protocol version and client identity.
Sequence Diagram
Click any step for details
Request
Response
Redirect
Internal
Step-by-Step Breakdown
1
Read the AI Catalog
Agent → Origin
2
Fetch the Server Card
Agent → MCP Server
3
Call server/discover
Agent → MCP Server
4
List tools
Agent → MCP Server
5
Call a tool
Agent → MCP Server
Token Inspector
Specs for this flow
Sections of the protocol that normatively define this flow, plus the security considerations that apply to it.