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Prompts Model Context Protocol · in the page specification/2026-07-28/server/prompts …omit the `_meta` request > metadata (`io.modelcontextprotocol/protocolVersion`, > `io.modelcontextprotocol/clientInfo`, and > `io.modelcontextprotocol/clientCapabilities`). Every request **MUST** incl… Resources Model Context Protocol · in the page specification/2026-07-28/server/resources …omit the `_meta` request > metadata (`io.modelcontextprotocol/protocolVersion`, > `io.modelcontextprotocol/clientInfo`, and > `io.modelcontextprotocol/clientCapabilities`). Every request **MUST** incl… Tools Model Context Protocol · in the page specification/2026-07-28/server/tools …omit the `_meta` request > metadata (`io.modelcontextprotocol/protocolVersion`, > `io.modelcontextprotocol/clientInfo`, and > `io.modelcontextprotocol/clientCapabilities`). Every request **MUST** incl… Caching Model Context Protocol · in the page specification/2026-07-28/server/utilities/caching …g heuristics or notifications. This should only occur in older server versions. * If `ttlMs` is negative, clients **SHOULD** ignore it and treat it as `0`. Servers **MUST** provide a `ttlMs` value th… Completion Model Context Protocol · in the page specification/2026-07-28/server/utilities/completion …omit the `_meta` request > metadata (`io.modelcontextprotocol/protocolVersion`, > `io.modelcontextprotocol/clientInfo`, and > `io.modelcontextprotocol/clientCapabilities`). Every request **MUST** incl… Logging Model Context Protocol · in the page specification/2026-07-28/server/utilities/logging …> > **Deprecated**: The Logging feature is deprecated as of protocol version > `2026-07-28` > ([SEP-2577](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2577)). > Under the [featur… Pagination Model Context Protocol · in the page specification/2026-07-28/server/utilities/pagination …omit the `_meta` request > metadata (`io.modelcontextprotocol/protocolVersion`, > `io.modelcontextprotocol/clientInfo`, and > `io.modelcontextprotocol/clientCapabilities`). Every request **MUST** incl… Architecture Model Context Protocol · in the page specification/draft/architecture/index …rotocol: every request is self-contained and carries its own protocol version and capabilities. This architecture enables users to integrate AI capabilities across applications while maintaining clear… Client Registration Model Context Protocol · in the page specification/draft/basic/authorization/client-registration …ion. This option is included for backwards compatibility with earlier versions of the MCP authorization spec. ### Application Type and Redirect URI Constraints When authorization servers support Ope… Authorization Model Context Protocol · in the page specification/draft/basic/authorization/index …owing implementations to adopt multiple extensions simultaneously * **Versioned independently** - Extensions follow the core MCP versioning cycle but may adopt independent versioning as needed A list… Overview Model Context Protocol · in the page specification/draft/basic/index …work together: * **Base Protocol**: Core JSON-RPC message types * **Versioning and Compatibility**: Protocol version negotiation, extension negotiation, and interoperability with earlier protocol re… Multi Round-Trip Requests Model Context Protocol · in the page specification/draft/basic/patterns/mrtr …> [!NOTE] > > Multi Round-Trip Requests (MRTR) was introduced in this version of the MCP > specification. This replaces the previous approach of sending server-initiated > requests. Servers **MUST** s… Subscriptions Model Context Protocol · in the page specification/draft/basic/patterns/subscriptions …, "params": { "_meta": { "io.modelcontextprotocol/protocolVersion": "2026-07-28", "io.modelcontextprotocol/clientInfo": { "name": "ExampleClient", "version": "1.0.0"… Overview Model Context Protocol · in the page specification/draft/basic/transports/index …adata travels in the message body: every request carries its protocol version and client capabilities in [`_meta.io.modelcontextprotocol/*`](https://modelcontextprotocol.io/specification/draft/basic/i… stdio Model Context Protocol · in the page specification/draft/basic/transports/stdio …ransport is carried inline in the JSON-RPC message body. The protocol version, per-request capabilities, and optional client identity live in [`_meta.io.modelcontextprotocol/*`][meta-fields]; the meth… Streamable HTTP Model Context Protocol · in the page specification/draft/basic/transports/streamable-http …amable HTTP > [!NOTE] > > Streamable HTTP was introduced in protocol version 2025-03-26 as a replacement > for the \[HTTP+SSE transport]\[http-sse] from protocol version 2024-11-05. > [!NOTE] > > Re… Elicitation Model Context Protocol · in the page specification/draft/client/elicitation …New feature:** URL mode elicitation is introduced in the `2025-11-25` version of the MCP specification. Its design and implementation may change in future protocol revisions. URL mode elicitation ena… Roots Model Context Protocol · in the page specification/draft/client/roots …G] > > **Deprecated**: The Roots feature is deprecated as of protocol version > `2026-07-28` > ([SEP-2577](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2577)). > Under the [featur… Sampling Model Context Protocol · in the page specification/draft/client/sampling …> > **Deprecated**: The Sampling feature is deprecated as of protocol version > `2026-07-28` > ([SEP-2577](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2577)). > Under the [featur… Schema Reference Model Context Protocol · in the page specification/draft/schema …link" data-typedoc-h="4">Deprecated</div><p>Deprecated as of protocol version 2026-07-28 (SEP-2577). Remains in the specification for at least twelve months; see the deprecated features registry.<… Discovery Model Context Protocol · in the page specification/draft/server/discover …`server/discover` lets a client query a server's supported protocol versions, capabilities, and identity before sending any other requests. Servers **MUST** implement it. ## Request The request ca… Prompts Model Context Protocol · in the page specification/draft/server/prompts …omit the `_meta` request > metadata (`io.modelcontextprotocol/protocolVersion`, > `io.modelcontextprotocol/clientInfo`, and > `io.modelcontextprotocol/clientCapabilities`). Every request **MUST** incl… Resources Model Context Protocol · in the page specification/draft/server/resources …omit the `_meta` request > metadata (`io.modelcontextprotocol/protocolVersion`, > `io.modelcontextprotocol/clientInfo`, and > `io.modelcontextprotocol/clientCapabilities`). Every request **MUST** incl… Tools Model Context Protocol · in the page specification/draft/server/tools …omit the `_meta` request > metadata (`io.modelcontextprotocol/protocolVersion`, > `io.modelcontextprotocol/clientInfo`, and > `io.modelcontextprotocol/clientCapabilities`). Every request **MUST** incl… Caching Model Context Protocol · in the page specification/draft/server/utilities/caching …g heuristics or notifications. This should only occur in older server versions. * If `ttlMs` is negative, clients **SHOULD** ignore it and treat it as `0`. Servers **MUST** provide a `ttlMs` value th… Completion Model Context Protocol · in the page specification/draft/server/utilities/completion …omit the `_meta` request > metadata (`io.modelcontextprotocol/protocolVersion`, > `io.modelcontextprotocol/clientInfo`, and > `io.modelcontextprotocol/clientCapabilities`). Every request **MUST** incl… Logging Model Context Protocol · in the page specification/draft/server/utilities/logging …> > **Deprecated**: The Logging feature is deprecated as of protocol version > `2026-07-28` > ([SEP-2577](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2577)). > Under the [featur… Pagination Model Context Protocol · in the page specification/draft/server/utilities/pagination …omit the `_meta` request > metadata (`io.modelcontextprotocol/protocolVersion`, > `io.modelcontextprotocol/clientInfo`, and > `io.modelcontextprotocol/clientCapabilities`). Every request **MUST** incl…