1,018 pages for server.

SEP-1303: Input Validation Errors as Tool Execution Errors Model Context Protocol · in the page seps/1303-input-validation-errors-as-tool-execution-errors …ecification](https://modelcontextprotocol.io/specification/2025-06-18/server/tools#error-handling) currently provides ambiguous guidance: * "Invalid arguments" should be treated as Protocol Error * "… SEP-1319: Decouple Request Payload from RPC Methods Definition Model Context Protocol · in the page seps/1319-decouple-request-payload-from-rpc-methods-definiti …compatible, requiring no changes from existing, compliant clients and servers. In short, this change is a strategic, foundational improvement that enables future growth without penalizing the current… SEP-1330: Elicitation Enum Schema Improvements and Standards Compliance Model Context Protocol · in the page seps/1330-elicitation-enum-schema-improvements-and-standards …Allows multiple selection of enumerated values to be returned to the server ## Specification ### 1. Mark Current `EnumSchema` with Non-Standard `enumNames` Property as "Legacy" The current MCP spe… SEP-1577: Sampling With Tools Model Context Protocol · in the page seps/1577--sampling-with-tools …ling/createMessage` and soft-deprecates `includeContext` (fences `thisServer` & `allServers` under a capability). This allows MCP servers to run their own agentic loops using the client's tokens (stil… SEP-1613: Establish JSON Schema 2020-12 as Default Dialect for MCP Model Context Protocol · in the page seps/1613-establish-json-schema-2020-12-as-default-dialect-f …schemas. This has caused: * Validation failures between clients and servers assuming different versions * Implementation divergence across SDK ecosystems * Developer uncertainty requiring arbitrary… SEP-1686: Tasks Model Context Protocol · in the page seps/1686-tasks …, which can be used to query the state and results of a task, up to a server-defined duration after the task has completed. This primitive is designed to augment other requests (such as tool calls) to… SEP-1730: SDKs Tiering System Model Context Protocol · in the page seps/1730-sdks-tiering-system …d way to know which SDKs support specific MCP features (OAuth, client/server/system features, like sampling, transports) * **Maintenance Expectations**: Unclear commitment levels for bug fixes, securi… SEP-1865: MCP Apps - Interactive User Interfaces for MCP Model Context Protocol · in the page seps/1865-mcp-apps-interactive-user-interfaces-for-mcp …ct This SEP proposes an extension to MCP (per SEP-1724) that enables servers to deliver interactive user interfaces to hosts. MCP Apps introduces a standardized pattern for declaring UI resources via… SEP-2106: Tools `inputSchema` & `outputSchema` Conform to JSON Schema 2020-12 Model Context Protocol · in the page seps/2106-json-schema-2020-12 ….) * **`outputSchema`**: Fully supports JSON Schema 2020-12 since MCP servers may return any valid JSON * **`structuredContent`**: Accepts any JSON value validated by `outputSchema` This proposal ena… SEP-2133: Extensions Model Context Protocol · in the page seps/2133-extensions …equired fields. Extensions may have settings that are sent in client/server messages for fine-grained configuration. This SEP defines *Official Extensions* and *Experimental Extensions*. Experimenta… SEP-2149: MCP Group Governance and Charter Template Model Context Protocol · in the page seps/2149-working-group-charter-template …vice versa. | Level | Description | Privileges | | - | - | - | | **Observer** | Anyone interested in following the group's work | Read access, may attend meetings, limited discussion participation |… SEP-2164: Standardize Resource Not Found Error Code Model Context Protocol · in the page seps/2164-resource-not-found-error …ommends `-32002`](https://modelcontextprotocol.io/specification/draft/server/resources#error-handling) as the error code for resource not found. However, `-32002` falls within the JSON-RPC "server err… SEP-2207: OIDC-Flavored Refresh Token Guidance Model Context Protocol · in the page seps/2207-oidc-refresh-token-guidance …refresh token issuance and requests, particularly when Authorization Servers support the `offline_access` scope. The `offline_access` scope originated in OIDC but can be adopted by any OAuth 2.1 Auth… SEP-2243: HTTP Header Standardization for Streamable HTTP Transport Model Context Protocol · in the page seps/2243-http-standardization …for compliance with the MCP version in which they are introduced. **Server Behavior**: Servers that process the request body MUST reject requests where the values specified in the headers do not mat… SEP-2322: Multi Round-Trip Requests Model Context Protocol · in the page seps/2322-MRTR …) | *** ## Abstract This proposal specifies a simple way to handle server-initiated requests in the context of a client-initiated request (e.g., an elicitation request in the context of a tool call… SEP-2468: Recommend Issuer (iss) Parameter in MCP Auth Responses Model Context Protocol · in the page seps/2468-recommend-issuer-claim-for-auth …tacks. By binding authorization responses to a specific authorization server identity, MCP clients can reliably detect and reject responses originating from an unexpected issuer, improving protocol ro… SEP-2484: Require Conformance Tests for Standards Track SEPs to Reach Final Status Model Context Protocol · in the page seps/2484-conformance-tests-required-for-final-seps …//github.com/modelcontextprotocol/conformance/blob/main/src/scenarios/server/json-schema-2020-12.ts) — SEP-1613 * [`ElicitationDefaultsScenario`](https://github.com/modelcontextprotocol/conformance/bl… SEP-2549: TTL for List Results Model Context Protocol · in the page seps/2549-TTL-for-list-results …ng. This allows clients to cache feature lists and reduce reliance on server-push notifications while remaining fully backward compatible. The `cacheScope` field controls who may cache a response. TTL… SEP-2567: Sessionless MCP via Explicit State Handles Model Context Protocol · in the page seps/2567-sessionless-mcp …cept from MCP, replacing implicit session-scoped state with explicit, server-minted state handles that the model carries and threads through subsequent calls. [SEP-2575] removes the `initialize` hands… SEP-2575: Make MCP Stateless Model Context Protocol · in the page seps/2575-stateless-mcp …ion handshake that establishes a session state between the client and server, which persists for the duration of the connection. This inherent statefulness makes it difficult to run MCP at scale. Pla… SEP-2577: Deprecate Roots, Sampling, and Logging Model Context Protocol · in the page seps/2577-deprecate-roots-sampling-and-logging …s in the core specification increases the burden for every client and server, slows protocol evolution, and makes the specification harder to learn. The following three features meet these criteria.… SEP-2596: Specification Feature Lifecycle and Deprecation Policy Model Context Protocol · in the page seps/2596-spec-feature-lifecycle-and-deprecation …], with no stated removal date. * The `includeContext` values `"thisServer"` and `"allServers"` are labeled "soft-deprecated" in [`sampling/createMessage`][sampling-includecontext] and in `schema.… SEP-2640: Skills Extension Model Context Protocol · in the page seps/2640-skills-extension …may be read directly; a `skills/list` method enumerates the skills a server serves (servers whose skill catalogs are large, generated, or otherwise unenumerable MAY return an empty or partial listing… SEP-2663: Tasks Extension Model Context Protocol · in the page seps/2663-tasks-extension …663) | *** ## Abstract This SEP defines an extension that allows a server to respond to a `tools/call` request with an asynchronous *task handle* instead of a final result, allowing the client to r… SEP-973: Expose additional metadata for Implementations, Resources, Tools and Prompts Model Context Protocol · in the page seps/973-expose-additional-metadata-for-implementations-res …ool`, `Resource` and `Prompt` schemas. While this can be used by both servers and clients for all implementations, we expect it to be used initially for server-provided implementations. ## Motivation… SEP-985: Align OAuth 2.0 Protected Resource Metadata with RFC 9728 Model Context Protocol · in the page seps/985-align-oauth-20-protected-resource-metadata-with-rf …centralized authentication service separate from the backend resource servers. In such deployments, injecting WWW-Authenticate headers from backend services is non-trivial due to separation of concern… SEP-990: Enable enterprise IdP policy controls during MCP OAuth flows Model Context Protocol · in the page seps/990-enable-enterprise-idp-policy-controls-during-mcp-o …enterprise admins, this enables visibility and control over which MCP Servers are able to be used within the organization. ## How Has This Been Tested? We have an end to end implementation of this [… SEP-991: Enable URL-based Client Registration using OAuth Client ID Metadata Documents Model Context Protocol · in the page seps/991-enable-url-based-client-registration-using-oauth-c …t metadata. This specifically addresses the common MCP scenario where servers and clients have no pre-existing relationship, enabling servers to trust clients without pre-coordination while maintainin… SEP-994: Shared Communication Practices/Guidelines Model Context Protocol · in the page seps/994-shared-communication-practicesguidelines …process defined in SECURITY.md. ### Discord Guidelines The Discord server is designed for **MCP contributors** and is not intended for general MCP support. #### Public Channels (Default) * Open c… Specification Enhancement Proposals (SEPs) Model Context Protocol · in the page seps/index …dge> | Standards Track | 2026-02-03 | | [SEP-2260](/seps/2260-Require-Server-requests-to-be-associated-with-Client-requests) | Require Server requests to be associated with a Client request. | <Badge… Architecture Model Context Protocol · in the page specification/2024-11-05/architecture/index …Architecture The Model Context Protocol (MCP) follows a client-host-server architecture where each host can run multiple client instances. This architecture enables users to integrate AI capabilitie… Overview Model Context Protocol · in the page specification/2024-11-05/basic/index # Overview All messages between MCP clients and servers **MUST** follow the [JSON-RPC 2.0](https://www.jsonrpc.org/specification) specification. The protocol defines three fundamental types of messag… Lifecycle Model Context Protocol · in the page specification/2024-11-05/basic/lifecycle …Model Context Protocol (MCP) defines a rigorous lifecycle for client-server connections that ensures proper capability negotiation and state management. 1. **Initialization**: Capability negotiation… Messages Model Context Protocol · in the page specification/2024-11-05/basic/messages …s of messages: ## Requests Requests are sent from the client to the server or vice versa. ```typescript theme={null} { jsonrpc: "2.0"; id: string | number; method: string; params?: { [k… Transports Model Context Protocol · in the page specification/2024-11-05/basic/transports …s MCP currently defines two standard transport mechanisms for client-server communication: 1. [stdio](#stdio), communication over standard in and standard out 2. [HTTP with Server-Sent Events](#http… Cancellation Model Context Protocol · in the page specification/2024-11-05/basic/utilities/cancellation …aid theme={null} sequenceDiagram participant Client participant Server Client->>Server: Request (ID: 123) Note over Server: Processing starts Client--)Server: notifications/cancelled (… Ping Model Context Protocol · in the page specification/2024-11-05/basic/utilities/ping …ented through a simple request/response pattern. Either the client or server can initiate a ping by sending a `ping` request. ## Message Format A ping request is a standard JSON-RPC request with no… Roots Model Context Protocol · in the page specification/2024-11-05/client/roots …ovides a standardized way for clients to expose filesystem "roots" to servers. Roots define the boundaries of where servers can operate within the filesystem, allowing them to understand which directo… Sampling Model Context Protocol · in the page specification/2024-11-05/client/sampling …ing The Model Context Protocol (MCP) provides a standardized way for servers to request LLM sampling ("completions" or "generations") from language models via clients. This flow allows clients to mai… Specification Model Context Protocol · in the page specification/2024-11-05/index …connections * **Clients**: Connectors within the host application * **Servers**: Services that provide context and capabilities MCP takes some inspiration from the [Language Server Protocol](https://… Architecture Model Context Protocol · in the page specification/2025-03-26/architecture/index …Architecture The Model Context Protocol (MCP) follows a client-host-server architecture where each host can run multiple client instances. This architecture enables users to integrate AI capabilitie… Authorization Model Context Protocol · in the page specification/2025-03-26/basic/authorization …nsport level, enabling MCP clients to make requests to restricted MCP servers on behalf of resource owners. This specification defines the authorization flow for HTTP-based transports. ### Protocol R… Overview Model Context Protocol · in the page specification/2025-03-26/basic/index …ion initialization, capability negotiation, and session control * **Server Features**: Resources, prompts, and tools exposed by servers * **Client Features**: Sampling and root directory lists provi… Lifecycle Model Context Protocol · in the page specification/2025-03-26/basic/lifecycle …Model Context Protocol (MCP) defines a rigorous lifecycle for client-server connections that ensures proper capability negotiation and state management. 1. **Initialization**: Capability negotiation… Transports Model Context Protocol · in the page specification/2025-03-26/basic/transports …otocol currently defines two standard transport mechanisms for client-server communication: 1. [stdio](#stdio), communication over standard in and standard out 2. [Streamable HTTP](#streamable-http)… Cancellation Model Context Protocol · in the page specification/2025-03-26/basic/utilities/cancellation …aid theme={null} sequenceDiagram participant Client participant Server Client->>Server: Request (ID: 123) Note over Server: Processing starts Client--)Server: notifications/cancelled (… Ping Model Context Protocol · in the page specification/2025-03-26/basic/utilities/ping …ented through a simple request/response pattern. Either the client or server can initiate a ping by sending a `ping` request. ## Message Format A ping request is a standard JSON-RPC request with no… Roots Model Context Protocol · in the page specification/2025-03-26/client/roots …ovides a standardized way for clients to expose filesystem "roots" to servers. Roots define the boundaries of where servers can operate within the filesystem, allowing them to understand which directo… Sampling Model Context Protocol · in the page specification/2025-03-26/client/sampling …ing The Model Context Protocol (MCP) provides a standardized way for servers to request LLM sampling ("completions" or "generations") from language models via clients. This flow allows clients to mai… Specification Model Context Protocol · in the page specification/2025-03-26/index …connections * **Clients**: Connectors within the host application * **Servers**: Services that provide context and capabilities MCP takes some inspiration from the [Language Server Protocol](https://…