Model Context Protocol Security: How the MCP Transport Layer Changes the Inspection Boundary
The Model Context Protocol standardizes how an LLM client connects to tool servers and exchanges context, tool calls, and tool results. The transport layer carries the agent identity, the tool call payloads, and the tool return values. The inspection boundary an MCP deployment owes is the HTTP leg between the MCP client and the MCP server. This piece walks through the transport modes MCP supports, the inspection target on each, the identity-aware policy decisions the deployment commits per call, and the audit record format that survives an Article 12 review.