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HomeDocsModel Context Protocol 20 Oct 2026
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Versioning changeddocs/2025-06-18/learn/versioning

Nearest release: v2.1.305, published under an hour before upstream edited the page. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

Upstream edited this page at 20 Oct 2026 20:02 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 22 Oct 2026 20:37 UTC.

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1818 receive backwards compatible changes.
1919* **Final**: past, complete specifications that will not be changed.
2020 
21The **current** protocol version is [**2025-11-25**](/specification/2025-11-25/).
21The **current** protocol version is [**2025-11-25**](/specification/2025-11-25.md).
2222 
2323## Feature States
2424 
2525Individual features of the specification may additionally be marked as
2626**Deprecated** under the
27[feature lifecycle and deprecation policy](/community/feature-lifecycle):
27[feature lifecycle and deprecation policy](/community/feature-lifecycle.md):
2828the feature remains part of the specification, but is scheduled for removal.
2929Deprecated features document a migration path (or state that none is required)
3030and remain in the specification for at least twelve months, or at least
3131ninety days under the policy's
32[expedited-removal exception](/community/feature-lifecycle#expedited-removal),
32[expedited-removal exception](/community/feature-lifecycle.md#expedited-removal),
3333before they become eligible for removal, after which they may be **Removed**
3434in a future revision.
3535 
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3636## Negotiation
3737 
3838Version negotiation happens during
39[initialization](/specification/2025-06-18/basic/lifecycle#initialization). Clients and
39[initialization](/specification/2025-06-18/basic/lifecycle.md#initialization). Clients and
4040servers **MAY** support multiple protocol versions simultaneously, but they **MUST**
4141agree on a single version to use for the session.
4242 
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