MCP implementation reference

This section is for MCP server and client implementers who need to diagnose behavior across a request path. It assumes familiarity with JSON-RPC and MCP; read Session lifecycle and State model first, then use the topic pages as a reference. It describes operational behavior at the MCP Runtime boundary and complements the MCP specification: the upstream server remains authoritative for MCP transport sessions and tool execution, while Runtime supplies routing, identity integration, and optional per-tool governance.

Topic	Reference
Session creation, expiry, disconnects	Session lifecycle
stdio, SSE, and Streamable HTTP	Transports
Tool metadata, discovery, and changes	Tool registration
Adapter, gateway, and upstream credentials	Auth propagation
Protocol, HTTP, and policy failures	Error reference
Per-call, transport-session, and platform state	State model

Runtime's public MCP endpoint is HTTP. Containerized servers must expose the HTTP endpoint configured by their MCPServer; a local stdio process is not itself a deployable Runtime endpoint. For product setup and client examples, see Client Connections, MCP OAuth, and the API reference.

The references distinguish MCP transport state from Runtime governance state. An MCP Mcp-Session-Id belongs to the upstream server. An MCPAgentSession belongs to Runtime's access model and binds identity, consent, expiry, and revocation. Creating, expiring, or reconnecting one does not create or restore the other.