890 pages for allow.

Protocol eras Model Context Protocol · in the page docs/draft/tools/inspector/protocol-eras …n a 2026-07-28 connection, because > server-to-client requests aren't allowed there. MRTR is its modern > replacement.  stops other web pages from driving the backend, but a request that arrives with **no** `Origin` hea… Web client Model Context Protocol · in the page docs/draft/tools/inspector/web …col/server-filesystem`, for instance, calls `roots/list` to learn its allowed directories. * **Headers**, **timeouts**, and **OAuth** fields. Headers are saved in the catalog as written; OAuth client… Understanding Authorization in MCP Model Context Protocol · in the page docs/draft/tutorials/security/authorization …er support) and retrieve another set of metadata properties that will allow it to know the endpoints it needs to complete the authorization flow. ```json theme={null} { "issuer": "https://auth.your… Local Server Security Model Context Protocol · in the page docs/draft/tutorials/security/local-server-security …, or pick a different server. > [!WARNING] > > Configuration-level allowlists are **cooperative boundaries**: a well-behaved > server respects them, but nothing in the protocol stops a malicious or… Security Best Practices Model Context Protocol · in the page docs/draft/tutorials/security/security_best_practices …pedia.org/wiki/Confused_deputy_problem)" vulnerabilities. This attack allows malicious clients to obtain authorization codes without proper user consent by exploiting the combination of static client… Example Servers Model Context Protocol · in the page examples …"@modelcontextprotocol/server-filesystem", "/path/to/allowed/files" ] } } } ``` ## Additional resources Visit our [GitHub Discussions](https://github.com/modelcontextpro… MCP Apps Model Context Protocol · in the page extensions/apps/overview …displays as part of the conversation. MCP Apps extend this pattern by allowing tools to declare a reference to an interactive UI in their tool description that the host renders in place. The core pat… Enterprise-Managed Authorization Model Context Protocol · in the page extensions/auth/enterprise-managed-authorization …authorization endpoint. 4. **Support organization configuration** — allow administrators to configure the enterprise IdP's endpoints, typically via organization-level settings rather than per-user s… Extensions Overview Model Context Protocol · in the page extensions/overview …oted into the core specification. The stage decides which changes are allowed, who approves them, and what implementers can expect. For full details, see [SEP-3392: Extension Lifecycle](https://modelc… Skills Model Context Protocol · in the page extensions/skills/overview …fication and documentation for Skills over MCP. The Skills extension allows MCP servers to expose workflow instructions and supporting files to clients. Clients can discover available skills, retriev… Frequently Asked Questions Model Context Protocol · in the page registry/faq …ublisher-provided` is preserved when publishing to the registry. This allows you to include custom metadata specific to your publishing process. > [!WARNING] > > There is a 4KB size limit (4096 bytes… MCP Registry Aggregators Model Context Protocol · in the page registry/registry-aggregators …in/docs/reference/api/openapi.yaml) defined by the MCP Registry. This allows clients, such as MCP host applications, to consume server metadata via a standardized interface. The subregistry OpenAPI s… Publishing Remote Servers Model Context Protocol · in the page registry/remote-servers …can coexist with the `packages` property in `server.json` in order to allow MCP host applications to choose the preferred method of installation. ```json server.json highlight={7-22} theme={null} {… Official MCP Registry Terms of Service Model Context Protocol · in the page registry/terms-of-service …out the Registry or the Model Context Protocol, then we (and those we allow) may use such information without obligation to you. 6. Branding. Only use the term “Official MCP Registry” where it is cle… Versioning Published MCP Servers Model Context Protocol · in the page registry/versioning …Recommended **(⚠️Caution!⚠️)** | | `2025.06.18` | non-semantic date | Allowed **(⚠️Caution!⚠️)** | | `2025-06-18` | non-semantic date | Allowed | | `v1.0` | prefixed version | Allowed | | `^1.2.3` | v… SEP-1024: MCP Client Security Requirements for Local Server Installation Model Context Protocol · in the page seps/1024-mcp-client-security-requirements-for-local-server- …ks explicit security requirements for client-side installation flows, allowing malicious actors to execute arbitrary commands on user systems through crafted MCP server configurations distributed via… SEP-1036: URL Mode Elicitation for secure out-of-band interactions Model Context Protocol · in the page seps/1036-url-mode-elicitation-for-secure-out-of-band-intera …f-band interaction started by URL mode elicitation is completed. This allows clients to react programmatically if appropriate. * The notification **MUST** only be sent to the client that initiated th… SEP-1046: Support OAuth client credentials flow in authorization Model Context Protocol · in the page seps/1046-support-oauth-client-credentials-flow-in-authoriza …c would be amended to list the OAuth client credentials flow as being allowed. Adhering to the patterns established by OAuth 2.1, the specification would RECOMMEND the use of asymmetric methods define… SEP-1302: Formalize Working Groups and Interest Groups in MCP Governance Model Context Protocol · in the page seps/1302-formalize-working-groups-and-interest-groups-in-mc …new protocol feature. The specification should be detailed enough to allow competing, interoperable implementations. A PR with the changes to the specification should be provided.* ### Interest Grou… SEP-1303: Input Validation Errors as Tool Execution Errors Model Context Protocol · in the page seps/1303-input-validation-errors-as-tool-execution-errors …models to receive validation error feedback in their context window, allowing them to self-correct and successfully complete tasks without human intervention, significantly improving task completion… SEP-1330: Elicitation Enum Schema Improvements and Standards Compliance Model Context Protocol · in the page seps/1330-elicitation-enum-schema-improvements-and-standards …* In `ElicitResponse`, add array as an `additionalProperty` type * Allows multiple selection of enumerated values to be returned to the server ## Specification ### 1. Mark Current `EnumSchema` wi… SEP-1577: Sampling With Tools Model Context Protocol · in the page seps/1577--sampling-with-tools …ontext` (fences `thisServer` & `allServers` under a capability). This allows MCP servers to run their own agentic loops using the client's tokens (still under the user supervision), and reduces the co… 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 …Current standard**: 2020-12 is the stable version as of 2025 ### Why allow explicit declaration? * Supports migration paths for existing schemas * Provides flexibility without protocol changes * Fol… SEP-1686: Tasks Model Context Protocol · in the page seps/1686-tasks …ss for other time-sensitive interactions. ***Ideal:*** Some method to allow agents to perform other work concurrently and get notified once long-running tasks complete. This SEP supports this use case… SEP-1699: Support SSE polling via server-side disconnect Model Context Protocol · in the page seps/1699-support-sse-polling-via-server-side-disconnect …ability. ## Motivation The Streamable HTTP transport spec [does not allow](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/04c6e1f0ea6544c7df307fb2d7c637efe34f58d3/docs/specificati… SEP-1730: SDKs Tiering System Model Context Protocol · in the page seps/1730-sdks-tiering-system …* **Tier 2** provides a clear pathway for improving SDKs * **Tier 3** allows experimentation without creating barriers to entry ### Why Time-Based Commitments? While the community raised concerns ab… SEP-1865: MCP Apps - Interactive User Interfaces for MCP Model Context Protocol · in the page seps/1865-mcp-apps-interactive-user-interfaces-for-mcp …edeclared resources (`ui://`), referenced by tools via metadata. This allows: * Hosts to prefetch templates before tool execution, improving performance * Separation of presentation (template) from d… SEP-2085: Governance Succession and Amendment Procedures Model Context Protocol · in the page seps/2085-governance-succession-and-amendment …uage describing the modification to existing governance provisions 3. Allow for a minimum comment period of five (5) days before voting 4. Be decided by recorded vote of Core Maintainers ## Rationale… SEP-2106: Tools `inputSchema` & `outputSchema` Conform to JSON Schema 2020-12 Model Context Protocol · in the page seps/2106-json-schema-2020-12 …eps `type: "object"` required (since tool arguments are objects), but allows any additional JSON Schema properties to support powerful validation compositions (`anyOf`, `oneOf`, `allOf`, etc.) * **`ou… SEP-2127: MCP Server Cards - HTTP Server Discovery Model Context Protocol · in the page seps/2127-mcp-server-cards …names where those concepts overlap reduces needless translation while allowing each owner to evolve its schema independently. ### Why Exclude Primitives? This specification intentionally omits primi… SEP-2133: Extensions Model Context Protocol · in the page seps/2133-extensions …nes a governance model and presentation structure for extensions that allows the MCP ecosystem to evolve while maintaining core protocol stability. Extensions enable experimentation with new capabilit… SEP-2207: OIDC-Flavored Refresh Token Guidance Model Context Protocol · in the page seps/2207-oidc-refresh-token-guidance …s that adopt this convention), the `offline_access` scope exists to allow clients to explicitly request refresh tokens, in addition to the OAuth logic. This creates several problems in the MCP ec… SEP-2243: HTTP Header Standardization for Streamable HTTP Transport Model Context Protocol · in the page seps/2243-http-standardization …y-Based Request Handling A server can expose a priority parameter to allow infrastructure to prioritize certain requests. **Tool Definition**: ```json theme={null} { "name": "generate_report",… SEP-2260: Require Server requests to be associated with a Client request. Model Context Protocol · in the page seps/2260-Require-Server-requests-to-be-associated-with-Client-requests …running JSON-RPC *request* from the client." Although the GET stream allows "unsolicited" requests, its use is entirely optional and cannot be relied upon by MCP Server authors. ### Design Intent T… SEP-2322: Multi Round-Trip Requests Model Context Protocol · in the page seps/2322-MRTR …persistent storage layer (e.g., PostgreSQL, Redis, DynamoDB), which allow multiple server instances to match up the elicitation response on one server instance with the original ongoing tool cal… SEP-2549: TTL for List Results Model Context Protocol · in the page seps/2549-TTL-for-list-results …ow long the response may be considered fresh before re-fetching. This allows clients to cache feature lists and reduce reliance on server-push notifications while remaining fully backward compatible.… SEP-2567: Sessionless MCP via Explicit State Handles Model Context Protocol · in the page seps/2567-sessionless-mcp …uest matches the one that created the session, so a leaked session ID allows hijack by any other authenticated principal.[^py-sdk-hijack] The "validate `(id, auth_context)` on every call" guidance bel… SEP-2575: Make MCP Stateless Model Context Protocol · in the page seps/2575-stateless-mcp …replacing it with discrete, stateless alternatives. This initial step allows each request to be processed independently, simplifying server-side logic and paving the way for robust, scalable deploymen… SEP-2577: Deprecate Roots, Sampling, and Logging Model Context Protocol · in the page seps/2577-deprecate-roots-sampling-and-logging …variables — all of which are more explicit. ### Sampling Sampling allows servers to request LLM completions from the client. While conceptually powerful, it has struggled with adoption: * **Compl… SEP-2596: Specification Feature Lifecycle and Deprecation Policy Model Context Protocol · in the page seps/2596-spec-feature-lifecycle-and-deprecation …ers with shorter windows for less mature features, which would have allowed the JSON-RPC batching reversal cited in [Motivation](#motivation) without a year-long deprecation. Whether MCP should ad… SEP-2640: Skills Extension Model Context Protocol · in the page seps/2640-skills-extension …rules as any other MCP-served skill, including the approval gate on `allowed-tools`. * **Publication is flat.** A nested skill is published like any other: through its own [`skills/list`](#enumeratio… SEP-2663: Tasks Extension Model Context Protocol · in the page seps/2663-tasks-extension …ol/pull/2663) | *** ## 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 cl… SEP-3392: Extension Lifecycle Model Context Protocol · in the page seps/3392-extension-lifecycle …ed when a stage changes. The stage decides which protocol changes are allowed, who approves them, and what stability implementers can expect. Experimental and Beta extensions iterate with Extension M… SEP-3398: Release Cycle Updates Model Context Protocol · in the page seps/3398-release-cycle-updates …it at the March release's calculated soft freeze. Only meetings that allow the full agenda lead time and voting period are scheduled. Planning for September 2027 begins in late January 2027. Plannin… 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 …-47fc30df9b23) ### Proposed State The proposed implementation would allow us to add visual affordances and links to documentation, making it easier to visually identify which servers/clients are pro… 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 …ack to requesting /.well-known/oauth-protected-resource. This change allows more flexible deployment models without removing existing capabilities. ```mermaid theme={null} sequenceDiagram partic… SEP-986: Specify Format for Tool Names Model Context Protocol · in the page seps/986-specify-format-for-tool-names …, and difficulties in documentation and automation. Standardizing the allowed characters and length will: * Make tool names predictable and interoperable across clients. * Allow for hierarchical and… 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 …tration mechanism for the Model Context Protocol (MCP). This approach allows OAuth clients to use HTTPS URLs as client identifiers, where the URL points to a JSON document containing client metadata.…