Agent-to-MCP-Server Authentication

Security Requirement

When an agent connects through an MCP client to an MCP server, authentication SHOULD use SPIFFE/SPIRE+mTLS (the service-to-service recommendation).

Preferred Approach: SPIFFE/SPIRE+mTLS

The agent (running as a workload) obtains a SVID from SPIRE and establishes an mTLS connection to the MCP server. Both parties authenticate each other via their SPIFFE IDs.

Agent (workload)
  → Obtains SVID from SPIRE Agent
  → MCP Client establishes mTLS to MCP Server
  → MCP Server validates agent's SPIFFE ID
  → MCP Server authorizes based on SPIFFE ID

Fallback Approach: OAuth with User Delegation