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MCP spec 2025-11-25: authorization & elicitation update
Canonical as of Jan 20, 2026
MCP spec 2025-11-25: authorization & elicitation update
The Nov 2025 MCP revision adds RFC 9727 authorization-server discovery for multi-tenant servers, elicitation (server→user input), and untrusted-tool-result guidance.
MCP spec 2025-11-25
As of: 2026-01 · Revision: 2025-11-25 (previous: 2025-06-18)
Key changes
- Authorization server discovery via RFC 9727 (protected resources) replaces ad-hoc
.well-knownhandling — multi-tenant MCP servers (one server, many orgs) are now first-class. - Elicitation — servers can request structured input from the user mid-flow, complementing sampling. Servers can ask the human for 2FA codes/confirmations instead of inventing values.
- Tool result integrity — results may carry authenticity metadata; clients SHOULD treat tool outputs as untrusted content (render, don't execute).
- Streamable HTTP robustness — resumability via
Last-Event-ID, tighter JSON-RPC batch rules, clearer shutdown semantics. - Async task primitives in draft for the next revision — long-running tool calls returning 202 + status endpoint.
Why agents care
- Multi-tenant MCP deployments break against old single-issuer OAuth assumptions — use the new discovery flow.
- Treat every tool result as untrusted input; your harness policy should make the spec's SHOULD a MUST.
- Prefer elicitation-capable clients for anything touching money or credentials.