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Progress Model Context Protocol · in the page specification/draft/basic/patterns/progress …al progress tracking for long-running operations through notification messages. The server **MAY** send progress notifications to report the status of requests the client has issued. ## Progress Flow… Subscriptions Model Context Protocol · in the page specification/draft/basic/patterns/subscriptions …**MUST** send `notifications/subscriptions/acknowledged` as the first message carrying the subscription's ID in `_meta` under `io.modelcontextprotocol/subscriptionId`, and **MUST NOT** send any notifi… Overview Model Context Protocol · in the page specification/draft/basic/transports/index …verview This page defines what a transport must provide to carry MCP messages, the standard transport bindings, and the requirements for defining new ones. Protocol semantics are identical on every… stdio Model Context Protocol · in the page specification/draft/basic/transports/stdio …over the subprocess's standard streams: * The server reads JSON-RPC messages from `stdin` and writes JSON-RPC messages to `stdout`. * Each message is a single JSON-RPC request, notification, or re… Streamable HTTP Model Context Protocol · in the page specification/draft/basic/transports/streamable-http …of a [`subscriptions/listen`][subscriptions-listen] request. See [Message Flow](#message-flow) for sequence diagrams of these interactions. The server **MUST** provide a single HTTP endpoint path… Versioning and Compatibility Model Context Protocol · in the page specification/draft/basic/versioning …"jsonrpc": "2.0", "id": 1, "error": { "code": -32022, "message": "Unsupported protocol version", "data": { "supported": ["2026-07-28", "2025-11-25"], "requested": "1900-… Elicitation Model Context Protocol · in the page specification/draft/client/elicitation …equests with modes that are not supported by the client. ## Protocol Messages ### Elicitation Requests Servers **MAY** request information from a user during the processing of a client request, by… Roots Model Context Protocol · in the page specification/draft/client/roots …clientCapabilities": { "roots": {} } } } ``` ## Protocol Messages ### Listing Roots To retrieve roots during the processing of a client request, servers send an `InputRequiredResult` co… Sampling Model Context Protocol · in the page specification/draft/client/sampling …eatures > registry](/specification/draft/deprecated.md). ## Protocol Messages ### Creating Messages To request a language model generation during the processing of a client request, servers send an… Specification Model Context Protocol · in the page specification/draft/index …workflows The protocol uses [JSON-RPC](https://www.jsonrpc.org/) 2.0 messages to establish communication between: * **Hosts**: LLM applications that initiate connections * **Clients**: Connectors wi… Schema Reference Model Context Protocol · in the page specification/draft/schema …></svg></a></div> </section> </div> <div class="type"> ### `JSONRPCMessage` <div class="tsd-signature"><span class="tsd-kind-type-alias">JSONRPCMessage</span><span class="tsd-signature-symbol">:… Prompts Model Context Protocol · in the page specification/draft/server/prompts …mpt templates to clients. Prompts allow servers to provide structured messages and instructions for interacting with language models. Clients can discover available prompts, retrieve their contents, a… Resources Model Context Protocol · in the page specification/draft/server/resources …credentials are per-request input, not connection state. ## Protocol Messages ### Listing Resources To discover available resources, clients send a `resources/list` request. This operation supports… Tools Model Context Protocol · in the page specification/draft/server/tools …ache hit rates when tools are included in model context. ## Protocol Messages ### Listing Tools To discover available tools, clients send a `tools/list` request. This operation supports [pagination… Completion Model Context Protocol · in the page specification/draft/server/utilities/completion …l} { "capabilities": { "completions": {} } } ``` ## Protocol Messages ### Requesting Completions To get completion suggestions, clients send a `completion/complete` request specifying what… Logging Model Context Protocol · in the page specification/draft/server/utilities/logging …(MCP) provides a standardized way for servers to send structured log messages to clients. Clients control logging verbosity per-request via `_meta`, with servers sending notifications containing seve…