<ul data-eligibleForWebStory="true"><li>MCP 2025-06-18 Spec Update enhances security with OAuth 2.0 Resource Server classification.</li><li>Structured JSON tool output supported, along with elicitation for user input mid-session.</li><li>New Security Considerations, PKCE protection, and token audience validation for MCP servers.</li><li>Added Security Best Practices with concrete countermeasures and structured output schema support.</li><li>Resource links in tool results, protocol version enforcement, and JSON-RPC batching removed.</li></ul>

MCP 2025-06-18 Spec Update: Security, Structured Output & Elicitation

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