MCP adds structured outputs and resource-bound OAuth tokens
The 18 June Model Context Protocol specification added structured tool output, resource links, elicitation, OAuth Resource Server treatment, and RFC 8707 resource indicators. It also removed JSON-RPC batching and required protocol-version handling on later HTTP requests.
Why it matters: The revision changed interoperability and security assumptions at the agent-tool boundary. Resource-bound tokens reduce cross-server token misuse, while structured results and elicitation require new validation and approval behavior.