Fetch an MCP server's tools and protocol revisions

On the MCP forms, “Fetch from server” lists the tools of the remote server at the version’s Remote URL and merges the ones you tick into the tool list, which stays editable by hand. The server connects anonymously to exactly the Remote URL and transport the form declares, with no /mcp or /sse path guessing and no fallback to the other transport, so the Remote URL must be the full MCP endpoint; it refuses internal addresses unless TOOL_DISCOVERY_ALLOWED_CIDRS allows them. The tool_discovery block of deploy/config.example.yaml holds the settings.

“Detect from server”, next to the Protocol versions field, uses the same connection to find the protocol revisions the server supports: each revision the registry’s MCP client speaks is offered in its own handshake, and the ones the server accepts unchanged are shown for review. “Use these” replaces the list; “Keep my list” leaves it as it is and offers the detected revisions as suggestions while typing. Revisions newer than the registry’s MCP client cannot be detected and are typed in by hand.