Kintone MCP Server

└── docs └── specification └── 2024-11-05 ├── _index.md ├── architecture └── _index.md ├── basic ├── _index.md ├── lifecycle.md ├── messages.md ├── transports.md └── utilities │ ├── _index.md │ ├── cancellation.md │ ├── ping.md │ └── progress.md ├── client ├── _index.md ├── roots.md └── sampling.md └── server ├── _index.md ├── prompts.md ├── resource-picker.png ├── resources.md ├── slash-command.png ├── tools.md └── utilities ├── _index.md ├── completion.md ├── logging.md └── pagination.md /docs/specification/2024-11-05/_index.md: -------------------------------------------------------------------------------- 1 | --- 2 | linkTitle: 2024-11-05 (Final) 3 | title: Model Context Protocol specification 4 | cascade: 5 | type: docs 6 | breadcrumbs: false 7 | weight: 2 8 | --- 9 | 10 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 11 | 12 | [Model Context Protocol](https://modelcontextprotocol.io) (MCP) is an open protocol that 13 | enables seamless integration between LLM applications and external data sources and 14 | tools. Whether you're building an AI-powered IDE, enhancing a chat interface, or creating 15 | custom AI workflows, MCP provides a standardized way to connect LLMs with the context 16 | they need. 17 | 18 | This specification defines the authoritative protocol requirements, based on the 19 | TypeScript schema in 20 | [schema.ts](https://github.com/modelcontextprotocol/specification/blob/main/schema/2024-11-05/schema.ts). 21 | 22 | For implementation guides and examples, visit 23 | [modelcontextprotocol.io](https://modelcontextprotocol.io). 24 | 25 | The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD 26 | NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be 27 | interpreted as described in [BCP 14](https://datatracker.ietf.org/doc/html/bcp14) 28 | [[RFC2119](https://datatracker.ietf.org/doc/html/rfc2119)] 29 | [[RFC8174](https://datatracker.ietf.org/doc/html/rfc8174)] when, and only when, they 30 | appear in all capitals, as shown here. 31 | 32 | ## Overview 33 | 34 | MCP provides a standardized way for applications to: 35 | 36 | - Share contextual information with language models 37 | - Expose tools and capabilities to AI systems 38 | - Build composable integrations and workflows 39 | 40 | The protocol uses [JSON-RPC](https://www.jsonrpc.org/) 2.0 messages to establish 41 | communication between: 42 | 43 | - **Hosts**: LLM applications that initiate connections 44 | - **Clients**: Connectors within the host application 45 | - **Servers**: Services that provide context and capabilities 46 | 47 | MCP takes some inspiration from the 48 | [Language Server Protocol](https://microsoft.github.io/language-server-protocol/), which 49 | standardizes how to add support for programming languages across a whole ecosystem of 50 | development tools. In a similar way, MCP standardizes how to integrate additional context 51 | and tools into the ecosystem of AI applications. 52 | 53 | ## Key Details 54 | 55 | ### Base Protocol 56 | 57 | - [JSON-RPC](https://www.jsonrpc.org/) message format 58 | - Stateful connections 59 | - Server and client capability negotiation 60 | 61 | ### Features 62 | 63 | Servers offer any of the following features to clients: 64 | 65 | - **Resources**: Context and data, for the user or the AI model to use 66 | - **Prompts**: Templated messages and workflows for users 67 | - **Tools**: Functions for the AI model to execute 68 | 69 | Clients may offer the following feature to servers: 70 | 71 | - **Sampling**: Server-initiated agentic behaviors and recursive LLM interactions 72 | 73 | ### Additional Utilities 74 | 75 | - Configuration 76 | - Progress tracking 77 | - Cancellation 78 | - Error reporting 79 | - Logging 80 | 81 | ## Security and Trust & Safety 82 | 83 | The Model Context Protocol enables powerful capabilities through arbitrary data access 84 | and code execution paths. With this power comes important security and trust 85 | considerations that all implementors must carefully address. 86 | 87 | ### Key Principles 88 | 89 | 1. **User Consent and Control** 90 | 91 | - Users must explicitly consent to and understand all data access and operations 92 | - Users must retain control over what data is shared and what actions are taken 93 | - Implementors should provide clear UIs for reviewing and authorizing activities 94 | 95 | 2. **Data Privacy** 96 | 97 | - Hosts must obtain explicit user consent before exposing user data to servers 98 | - Hosts must not transmit resource data elsewhere without user consent 99 | - User data should be protected with appropriate access controls 100 | 101 | 3. **Tool Safety** 102 | 103 | - Tools represent arbitrary code execution and must be treated with appropriate 104 | caution 105 | - Hosts must obtain explicit user consent before invoking any tool 106 | - Users should understand what each tool does before authorizing its use 107 | 108 | 4. **LLM Sampling Controls** 109 | - Users must explicitly approve any LLM sampling requests 110 | - Users should control: 111 | - Whether sampling occurs at all 112 | - The actual prompt that will be sent 113 | - What results the server can see 114 | - The protocol intentionally limits server visibility into prompts 115 | 116 | ### Implementation Guidelines 117 | 118 | While MCP itself cannot enforce these security principles at the protocol level, 119 | implementors **SHOULD**: 120 | 121 | 1. Build robust consent and authorization flows into their applications 122 | 2. Provide clear documentation of security implications 123 | 3. Implement appropriate access controls and data protections 124 | 4. Follow security best practices in their integrations 125 | 5. Consider privacy implications in their feature designs 126 | 127 | ## Learn More 128 | 129 | Explore the detailed specification for each protocol component: 130 | 131 | {{< cards >}} {{< card link="architecture" title="Architecture" icon="template" >}} 132 | {{< card link="basic" title="Base Protocol" icon="code" >}} 133 | {{< card link="server" title="Server Features" icon="server" >}} 134 | {{< card link="client" title="Client Features" icon="user" >}} 135 | {{< card link="contributing" title="Contributing" icon="pencil" >}} {{< /cards >}} 136 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/architecture/_index.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Architecture 3 | cascade: 4 | type: docs 5 | weight: 1 6 | --- 7 | 8 | The Model Context Protocol (MCP) follows a client-host-server architecture where each 9 | host can run multiple client instances. This architecture enables users to integrate AI 10 | capabilities across applications while maintaining clear security boundaries and 11 | isolating concerns. Built on JSON-RPC, MCP provides a stateful session protocol focused 12 | on context exchange and sampling coordination between clients and servers. 13 | 14 | ## Core Components 15 | 16 | ```mermaid 17 | graph LR 18 | subgraph "Application Host Process" 19 | H[Host] 20 | C1[Client 1] 21 | C2[Client 2] 22 | C3[Client 3] 23 | H --> C1 24 | H --> C2 25 | H --> C3 26 | end 27 | 28 | subgraph "Local machine" 29 | S1[Server 1<br>Files & Git] 30 | S2[Server 2<br>Database] 31 | R1[("Local<br>Resource A")] 32 | R2[("Local<br>Resource B")] 33 | 34 | C1 --> S1 35 | C2 --> S2 36 | S1 <--> R1 37 | S2 <--> R2 38 | end 39 | 40 | subgraph "Internet" 41 | S3[Server 3<br>External APIs] 42 | R3[("Remote<br>Resource C")] 43 | 44 | C3 --> S3 45 | S3 <--> R3 46 | end 47 | ``` 48 | 49 | ### Host 50 | 51 | The host process acts as the container and coordinator: 52 | 53 | - Creates and manages multiple client instances 54 | - Controls client connection permissions and lifecycle 55 | - Enforces security policies and consent requirements 56 | - Handles user authorization decisions 57 | - Coordinates AI/LLM integration and sampling 58 | - Manages context aggregation across clients 59 | 60 | ### Clients 61 | 62 | Each client is created by the host and maintains an isolated server connection: 63 | 64 | - Establishes one stateful session per server 65 | - Handles protocol negotiation and capability exchange 66 | - Routes protocol messages bidirectionally 67 | - Manages subscriptions and notifications 68 | - Maintains security boundaries between servers 69 | 70 | A host application creates and manages multiple clients, with each client having a 1:1 71 | relationship with a particular server. 72 | 73 | ### Servers 74 | 75 | Servers provide specialized context and capabilities: 76 | 77 | - Expose resources, tools and prompts via MCP primitives 78 | - Operate independently with focused responsibilities 79 | - Request sampling through client interfaces 80 | - Must respect security constraints 81 | - Can be local processes or remote services 82 | 83 | ## Design Principles 84 | 85 | MCP is built on several key design principles that inform its architecture and 86 | implementation: 87 | 88 | 1. **Servers should be extremely easy to build** 89 | 90 | - Host applications handle complex orchestration responsibilities 91 | - Servers focus on specific, well-defined capabilities 92 | - Simple interfaces minimize implementation overhead 93 | - Clear separation enables maintainable code 94 | 95 | 2. **Servers should be highly composable** 96 | 97 | - Each server provides focused functionality in isolation 98 | - Multiple servers can be combined seamlessly 99 | - Shared protocol enables interoperability 100 | - Modular design supports extensibility 101 | 102 | 3. **Servers should not be able to read the whole conversation, nor "see into" other 103 | servers** 104 | 105 | - Servers receive only necessary contextual information 106 | - Full conversation history stays with the host 107 | - Each server connection maintains isolation 108 | - Cross-server interactions are controlled by the host 109 | - Host process enforces security boundaries 110 | 111 | 4. **Features can be added to servers and clients progressively** 112 | - Core protocol provides minimal required functionality 113 | - Additional capabilities can be negotiated as needed 114 | - Servers and clients evolve independently 115 | - Protocol designed for future extensibility 116 | - Backwards compatibility is maintained 117 | 118 | ## Message Types 119 | 120 | MCP defines three core message types based on 121 | [JSON-RPC 2.0](https://www.jsonrpc.org/specification): 122 | 123 | - **Requests**: Bidirectional messages with method and parameters expecting a response 124 | - **Responses**: Successful results or errors matching specific request IDs 125 | - **Notifications**: One-way messages requiring no response 126 | 127 | Each message type follows the JSON-RPC 2.0 specification for structure and delivery 128 | semantics. 129 | 130 | ## Capability Negotiation 131 | 132 | The Model Context Protocol uses a capability-based negotiation system where clients and 133 | servers explicitly declare their supported features during initialization. Capabilities 134 | determine which protocol features and primitives are available during a session. 135 | 136 | - Servers declare capabilities like resource subscriptions, tool support, and prompt 137 | templates 138 | - Clients declare capabilities like sampling support and notification handling 139 | - Both parties must respect declared capabilities throughout the session 140 | - Additional capabilities can be negotiated through extensions to the protocol 141 | 142 | ```mermaid 143 | sequenceDiagram 144 | participant Host 145 | participant Client 146 | participant Server 147 | 148 | Host->>+Client: Initialize client 149 | Client->>+Server: Initialize session with capabilities 150 | Server-->>Client: Respond with supported capabilities 151 | 152 | Note over Host,Server: Active Session with Negotiated Features 153 | 154 | loop Client Requests 155 | Host->>Client: User- or model-initiated action 156 | Client->>Server: Request (tools/resources) 157 | Server-->>Client: Response 158 | Client-->>Host: Update UI or respond to model 159 | end 160 | 161 | loop Server Requests 162 | Server->>Client: Request (sampling) 163 | Client->>Host: Forward to AI 164 | Host-->>Client: AI response 165 | Client-->>Server: Response 166 | end 167 | 168 | loop Notifications 169 | Server--)Client: Resource updates 170 | Client--)Server: Status changes 171 | end 172 | 173 | Host->>Client: Terminate 174 | Client->>-Server: End session 175 | deactivate Server 176 | ``` 177 | 178 | Each capability unlocks specific protocol features for use during the session. For 179 | example: 180 | 181 | - Implemented [server features]({{< ref "/specification/2024-11-05/server" >}}) must be 182 | advertised in the server's capabilities 183 | - Emitting resource subscription notifications requires the server to declare 184 | subscription support 185 | - Tool invocation requires the server to declare tool capabilities 186 | - [Sampling]({{< ref "/specification/2024-11-05/client" >}}) requires the client to 187 | declare support in its capabilities 188 | 189 | This capability negotiation ensures clients and servers have a clear understanding of 190 | supported functionality while maintaining protocol extensibility. 191 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/basic/_index.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Base Protocol 3 | cascade: 4 | type: docs 5 | weight: 2 6 | --- 7 | 8 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 9 | 10 | All messages between MCP clients and servers **MUST** follow the 11 | [JSON-RPC 2.0](https://www.jsonrpc.org/specification) specification. The protocol defines 12 | three fundamental types of messages: 13 | 14 | | Type | Description | Requirements | 15 | | --------------- | -------------------------------------- | -------------------------------------- | 16 | | `Requests` | Messages sent to initiate an operation | Must include unique ID and method name | 17 | | `Responses` | Messages sent in reply to requests | Must include same ID as request | 18 | | `Notifications` | One-way messages with no reply | Must not include an ID | 19 | 20 | **Responses** are further sub-categorized as either **successful results** or **errors**. 21 | Results can follow any JSON object structure, while errors must include an error code and 22 | message at minimum. 23 | 24 | ## Protocol Layers 25 | 26 | The Model Context Protocol consists of several key components that work together: 27 | 28 | - **Base Protocol**: Core JSON-RPC message types 29 | - **Lifecycle Management**: Connection initialization, capability negotiation, and 30 | session control 31 | - **Server Features**: Resources, prompts, and tools exposed by servers 32 | - **Client Features**: Sampling and root directory lists provided by clients 33 | - **Utilities**: Cross-cutting concerns like logging and argument completion 34 | 35 | All implementations **MUST** support the base protocol and lifecycle management 36 | components. Other components **MAY** be implemented based on the specific needs of the 37 | application. 38 | 39 | These protocol layers establish clear separation of concerns while enabling rich 40 | interactions between clients and servers. The modular design allows implementations to 41 | support exactly the features they need. 42 | 43 | See the following pages for more details on the different components: 44 | 45 | {{< cards >}} 46 | {{< card link="/specification/2024-11-05/basic/lifecycle" title="Lifecycle" icon="refresh" >}} 47 | {{< card link="/specification/2024-11-05/server/resources" title="Resources" icon="document" >}} 48 | {{< card link="/specification/2024-11-05/server/prompts" title="Prompts" icon="chat-alt-2" >}} 49 | {{< card link="/specification/2024-11-05/server/tools" title="Tools" icon="adjustments" >}} 50 | {{< card link="/specification/2024-11-05/server/utilities/logging" title="Logging" icon="annotation" >}} 51 | {{< card link="/specification/2024-11-05/client/sampling" title="Sampling" icon="code" >}} 52 | {{< /cards >}} 53 | 54 | ## Auth 55 | 56 | Authentication and authorization are not currently part of the core MCP specification, 57 | but we are considering ways to introduce them in future. Join us in 58 | [GitHub Discussions](https://github.com/modelcontextprotocol/specification/discussions) 59 | to help shape the future of the protocol! 60 | 61 | Clients and servers **MAY** negotiate their own custom authentication and authorization 62 | strategies. 63 | 64 | ## Schema 65 | 66 | The full specification of the protocol is defined as a 67 | [TypeScript schema](http://github.com/modelcontextprotocol/specification/tree/main/schema/2024-11-05/schema.ts). 68 | This is the source of truth for all protocol messages and structures. 69 | 70 | There is also a 71 | [JSON Schema](http://github.com/modelcontextprotocol/specification/tree/main/schema/2024-11-05/schema.json), 72 | which is automatically generated from the TypeScript source of truth, for use with 73 | various automated tooling. 74 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/basic/lifecycle.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Lifecycle 3 | type: docs 4 | weight: 30 5 | --- 6 | 7 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 8 | 9 | The Model Context Protocol (MCP) defines a rigorous lifecycle for client-server 10 | connections that ensures proper capability negotiation and state management. 11 | 12 | 1. **Initialization**: Capability negotiation and protocol version agreement 13 | 2. **Operation**: Normal protocol communication 14 | 3. **Shutdown**: Graceful termination of the connection 15 | 16 | ```mermaid 17 | sequenceDiagram 18 | participant Client 19 | participant Server 20 | 21 | Note over Client,Server: Initialization Phase 22 | activate Client 23 | Client->>+Server: initialize request 24 | Server-->>Client: initialize response 25 | Client--)Server: initialized notification 26 | 27 | Note over Client,Server: Operation Phase 28 | rect rgb(200, 220, 250) 29 | note over Client,Server: Normal protocol operations 30 | end 31 | 32 | Note over Client,Server: Shutdown 33 | Client--)-Server: Disconnect 34 | deactivate Server 35 | Note over Client,Server: Connection closed 36 | ``` 37 | 38 | ## Lifecycle Phases 39 | 40 | ### Initialization 41 | 42 | The initialization phase **MUST** be the first interaction between client and server. 43 | During this phase, the client and server: 44 | 45 | - Establish protocol version compatibility 46 | - Exchange and negotiate capabilities 47 | - Share implementation details 48 | 49 | The client **MUST** initiate this phase by sending an `initialize` request containing: 50 | 51 | - Protocol version supported 52 | - Client capabilities 53 | - Client implementation information 54 | 55 | ```json 56 | { 57 | "jsonrpc": "2.0", 58 | "id": 1, 59 | "method": "initialize", 60 | "params": { 61 | "protocolVersion": "2024-11-05", 62 | "capabilities": { 63 | "roots": { 64 | "listChanged": true 65 | }, 66 | "sampling": {} 67 | }, 68 | "clientInfo": { 69 | "name": "ExampleClient", 70 | "version": "1.0.0" 71 | } 72 | } 73 | } 74 | ``` 75 | 76 | The server **MUST** respond with its own capabilities and information: 77 | 78 | ```json 79 | { 80 | "jsonrpc": "2.0", 81 | "id": 1, 82 | "result": { 83 | "protocolVersion": "2024-11-05", 84 | "capabilities": { 85 | "logging": {}, 86 | "prompts": { 87 | "listChanged": true 88 | }, 89 | "resources": { 90 | "subscribe": true, 91 | "listChanged": true 92 | }, 93 | "tools": { 94 | "listChanged": true 95 | } 96 | }, 97 | "serverInfo": { 98 | "name": "ExampleServer", 99 | "version": "1.0.0" 100 | } 101 | } 102 | } 103 | ``` 104 | 105 | After successful initialization, the client **MUST** send an `initialized` notification 106 | to indicate it is ready to begin normal operations: 107 | 108 | ```json 109 | { 110 | "jsonrpc": "2.0", 111 | "method": "notifications/initialized" 112 | } 113 | ``` 114 | 115 | - The client **SHOULD NOT** send requests other than 116 | [pings]({{< ref "/specification/2024-11-05/basic/utilities/ping" >}}) before the server 117 | has responded to the `initialize` request. 118 | - The server **SHOULD NOT** send requests other than 119 | [pings]({{< ref "/specification/2024-11-05/basic/utilities/ping" >}}) and 120 | [logging]({{< ref "/specification/2024-11-05/server/utilities/logging" >}}) before 121 | receiving the `initialized` notification. 122 | 123 | #### Version Negotiation 124 | 125 | In the `initialize` request, the client **MUST** send a protocol version it supports. 126 | This **SHOULD** be the _latest_ version supported by the client. 127 | 128 | If the server supports the requested protocol version, it **MUST** respond with the same 129 | version. Otherwise, the server **MUST** respond with another protocol version it 130 | supports. This **SHOULD** be the _latest_ version supported by the server. 131 | 132 | If the client does not support the version in the server's response, it **SHOULD** 133 | disconnect. 134 | 135 | #### Capability Negotiation 136 | 137 | Client and server capabilities establish which optional protocol features will be 138 | available during the session. 139 | 140 | Key capabilities include: 141 | 142 | | Category | Capability | Description | 143 | | -------- | -------------- | ------------------------------------------------------------------------------------------------- | 144 | | Client | `roots` | Ability to provide filesystem [roots]({{< ref "/specification/2024-11-05/client/roots" >}}) | 145 | | Client | `sampling` | Support for LLM [sampling]({{< ref "/specification/2024-11-05/client/sampling" >}}) requests | 146 | | Client | `experimental` | Describes support for non-standard experimental features | 147 | | Server | `prompts` | Offers [prompt templates]({{< ref "/specification/2024-11-05/server/prompts" >}}) | 148 | | Server | `resources` | Provides readable [resources]({{< ref "/specification/2024-11-05/server/resources" >}}) | 149 | | Server | `tools` | Exposes callable [tools]({{< ref "/specification/2024-11-05/server/tools" >}}) | 150 | | Server | `logging` | Emits structured [log messages]({{< ref "/specification/2024-11-05/server/utilities/logging" >}}) | 151 | | Server | `experimental` | Describes support for non-standard experimental features | 152 | 153 | Capability objects can describe sub-capabilities like: 154 | 155 | - `listChanged`: Support for list change notifications (for prompts, resources, and 156 | tools) 157 | - `subscribe`: Support for subscribing to individual items' changes (resources only) 158 | 159 | ### Operation 160 | 161 | During the operation phase, the client and server exchange messages according to the 162 | negotiated capabilities. 163 | 164 | Both parties **SHOULD**: 165 | 166 | - Respect the negotiated protocol version 167 | - Only use capabilities that were successfully negotiated 168 | 169 | ### Shutdown 170 | 171 | During the shutdown phase, one side (usually the client) cleanly terminates the protocol 172 | connection. No specific shutdown messages are defined—instead, the underlying transport 173 | mechanism should be used to signal connection termination: 174 | 175 | #### stdio 176 | 177 | For the stdio [transport]({{< ref "/specification/2024-11-05/basic/transports" >}}), the 178 | client **SHOULD** initiate shutdown by: 179 | 180 | 1. First, closing the input stream to the child process (the server) 181 | 2. Waiting for the server to exit, or sending `SIGTERM` if the server does not exit 182 | within a reasonable time 183 | 3. Sending `SIGKILL` if the server does not exit within a reasonable time after `SIGTERM` 184 | 185 | The server **MAY** initiate shutdown by closing its output stream to the client and 186 | exiting. 187 | 188 | #### HTTP 189 | 190 | For HTTP [transports]({{< ref "/specification/2024-11-05/basic/transports" >}}), shutdown 191 | is indicated by closing the associated HTTP connection(s). 192 | 193 | ## Error Handling 194 | 195 | Implementations **SHOULD** be prepared to handle these error cases: 196 | 197 | - Protocol version mismatch 198 | - Failure to negotiate required capabilities 199 | - Initialize request timeout 200 | - Shutdown timeout 201 | 202 | Implementations **SHOULD** implement appropriate timeouts for all requests, to prevent 203 | hung connections and resource exhaustion. 204 | 205 | Example initialization error: 206 | 207 | ```json 208 | { 209 | "jsonrpc": "2.0", 210 | "id": 1, 211 | "error": { 212 | "code": -32602, 213 | "message": "Unsupported protocol version", 214 | "data": { 215 | "supported": ["2024-11-05"], 216 | "requested": "1.0.0" 217 | } 218 | } 219 | } 220 | ``` 221 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/basic/messages.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Messages 3 | type: docs 4 | weight: 20 5 | --- 6 | 7 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 8 | 9 | All messages in MCP **MUST** follow the 10 | [JSON-RPC 2.0](https://www.jsonrpc.org/specification) specification. The protocol defines 11 | three types of messages: 12 | 13 | ## Requests 14 | 15 | Requests are sent from the client to the server or vice versa. 16 | 17 | ```typescript 18 | { 19 | jsonrpc: "2.0"; 20 | id: string | number; 21 | method: string; 22 | params?: { 23 | [key: string]: unknown; 24 | }; 25 | } 26 | ``` 27 | 28 | - Requests **MUST** include a string or integer ID. 29 | - Unlike base JSON-RPC, the ID **MUST NOT** be `null`. 30 | - The request ID **MUST NOT** have been previously used by the requestor within the same 31 | session. 32 | 33 | ## Responses 34 | 35 | Responses are sent in reply to requests. 36 | 37 | ```typescript 38 | { 39 | jsonrpc: "2.0"; 40 | id: string | number; 41 | result?: { 42 | [key: string]: unknown; 43 | } 44 | error?: { 45 | code: number; 46 | message: string; 47 | data?: unknown; 48 | } 49 | } 50 | ``` 51 | 52 | - Responses **MUST** include the same ID as the request they correspond to. 53 | - Either a `result` or an `error` **MUST** be set. A response **MUST NOT** set both. 54 | - Error codes **MUST** be integers. 55 | 56 | ## Notifications 57 | 58 | Notifications are sent from the client to the server or vice versa. They do not expect a 59 | response. 60 | 61 | ```typescript 62 | { 63 | jsonrpc: "2.0"; 64 | method: string; 65 | params?: { 66 | [key: string]: unknown; 67 | }; 68 | } 69 | ``` 70 | 71 | - Notifications **MUST NOT** include an ID. 72 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/basic/transports.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Transports 3 | type: docs 4 | weight: 40 5 | --- 6 | 7 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 8 | 9 | MCP currently defines two standard transport mechanisms for client-server communication: 10 | 11 | 1. [stdio](#stdio), communication over standard in and standard out 12 | 2. [HTTP with Server-Sent Events](#http-with-sse) (SSE) 13 | 14 | Clients **SHOULD** support stdio whenever possible. 15 | 16 | It is also possible for clients and servers to implement 17 | [custom transports](#custom-transports) in a pluggable fashion. 18 | 19 | ## stdio 20 | 21 | In the **stdio** transport: 22 | 23 | - The client launches the MCP server as a subprocess. 24 | - The server receives JSON-RPC messages on its standard input (`stdin`) and writes 25 | responses to its standard output (`stdout`). 26 | - Messages are delimited by newlines, and **MUST NOT** contain embedded newlines. 27 | - The server **MAY** write UTF-8 strings to its standard error (`stderr`) for logging 28 | purposes. Clients **MAY** capture, forward, or ignore this logging. 29 | - The server **MUST NOT** write anything to its `stdout` that is not a valid MCP message. 30 | - The client **MUST NOT** write anything to the server's `stdin` that is not a valid MCP 31 | message. 32 | 33 | ```mermaid 34 | sequenceDiagram 35 | participant Client 36 | participant Server Process 37 | 38 | Client->>+Server Process: Launch subprocess 39 | loop Message Exchange 40 | Client->>Server Process: Write to stdin 41 | Server Process->>Client: Write to stdout 42 | Server Process--)Client: Optional logs on stderr 43 | end 44 | Client->>Server Process: Close stdin, terminate subprocess 45 | deactivate Server Process 46 | ``` 47 | 48 | ## HTTP with SSE 49 | 50 | In the **SSE** transport, the server operates as an independent process that can handle 51 | multiple client connections. 52 | 53 | The server **MUST** provide two endpoints: 54 | 55 | 1. An SSE endpoint, for clients to establish a connection and receive messages from the 56 | server 57 | 2. A regular HTTP POST endpoint for clients to send messages to the server 58 | 59 | When a client connects, the server **MUST** send an `endpoint` event containing a URI for 60 | the client to use for sending messages. All subsequent client messages **MUST** be sent 61 | as HTTP POST requests to this endpoint. 62 | 63 | Server messages are sent as SSE `message` events, with the message content encoded as 64 | JSON in the event data. 65 | 66 | ```mermaid 67 | sequenceDiagram 68 | participant Client 69 | participant Server 70 | 71 | Client->>Server: Open SSE connection 72 | Server->>Client: endpoint event 73 | loop Message Exchange 74 | Client->>Server: HTTP POST messages 75 | Server->>Client: SSE message events 76 | end 77 | Client->>Server: Close SSE connection 78 | ``` 79 | 80 | ## Custom Transports 81 | 82 | Clients and servers **MAY** implement additional custom transport mechanisms to suit 83 | their specific needs. The protocol is transport-agnostic and can be implemented over any 84 | communication channel that supports bidirectional message exchange. 85 | 86 | Implementers who choose to support custom transports **MUST** ensure they preserve the 87 | JSON-RPC message format and lifecycle requirements defined by MCP. Custom transports 88 | **SHOULD** document their specific connection establishment and message exchange patterns 89 | to aid interoperability. 90 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/basic/utilities/_index.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Utilities 3 | --- 4 | 5 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 6 | 7 | These optional features enhance the base protocol functionality with various utilities. 8 | 9 | {{< cards >}} {{< card link="ping" title="Ping" icon="status-online" >}} 10 | {{< card link="cancellation" title="Cancellation" icon="x" >}} 11 | {{< card link="progress" title="Progress" icon="clock" >}} {{< /cards >}} 12 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/basic/utilities/cancellation.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Cancellation 3 | weight: 10 4 | --- 5 | 6 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 7 | 8 | The Model Context Protocol (MCP) supports optional cancellation of in-progress requests 9 | through notification messages. Either side can send a cancellation notification to 10 | indicate that a previously-issued request should be terminated. 11 | 12 | ## Cancellation Flow 13 | 14 | When a party wants to cancel an in-progress request, it sends a `notifications/cancelled` 15 | notification containing: 16 | 17 | - The ID of the request to cancel 18 | - An optional reason string that can be logged or displayed 19 | 20 | ```json 21 | { 22 | "jsonrpc": "2.0", 23 | "method": "notifications/cancelled", 24 | "params": { 25 | "requestId": "123", 26 | "reason": "User requested cancellation" 27 | } 28 | } 29 | ``` 30 | 31 | ## Behavior Requirements 32 | 33 | 1. Cancellation notifications **MUST** only reference requests that: 34 | - Were previously issued in the same direction 35 | - Are believed to still be in-progress 36 | 2. The `initialize` request **MUST NOT** be cancelled by clients 37 | 3. Receivers of cancellation notifications **SHOULD**: 38 | - Stop processing the cancelled request 39 | - Free associated resources 40 | - Not send a response for the cancelled request 41 | 4. Receivers **MAY** ignore cancellation notifications if: 42 | - The referenced request is unknown 43 | - Processing has already completed 44 | - The request cannot be cancelled 45 | 5. The sender of the cancellation notification **SHOULD** ignore any response to the 46 | request that arrives afterward 47 | 48 | ## Timing Considerations 49 | 50 | Due to network latency, cancellation notifications may arrive after request processing 51 | has completed, and potentially after a response has already been sent. 52 | 53 | Both parties **MUST** handle these race conditions gracefully: 54 | 55 | ```mermaid 56 | sequenceDiagram 57 | participant Client 58 | participant Server 59 | 60 | Client->>Server: Request (ID: 123) 61 | Note over Server: Processing starts 62 | Client--)Server: notifications/cancelled (ID: 123) 63 | alt 64 | Note over Server: Processing may have<br/>completed before<br/>cancellation arrives 65 | else If not completed 66 | Note over Server: Stop processing 67 | end 68 | ``` 69 | 70 | ## Implementation Notes 71 | 72 | - Both parties **SHOULD** log cancellation reasons for debugging 73 | - Application UIs **SHOULD** indicate when cancellation is requested 74 | 75 | ## Error Handling 76 | 77 | Invalid cancellation notifications **SHOULD** be ignored: 78 | 79 | - Unknown request IDs 80 | - Already completed requests 81 | - Malformed notifications 82 | 83 | This maintains the "fire and forget" nature of notifications while allowing for race 84 | conditions in asynchronous communication. 85 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/basic/utilities/ping.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Ping 3 | weight: 5 4 | --- 5 | 6 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 7 | 8 | The Model Context Protocol includes an optional ping mechanism that allows either party 9 | to verify that their counterpart is still responsive and the connection is alive. 10 | 11 | ## Overview 12 | 13 | The ping functionality is implemented through a simple request/response pattern. Either 14 | the client or server can initiate a ping by sending a `ping` request. 15 | 16 | ## Message Format 17 | 18 | A ping request is a standard JSON-RPC request with no parameters: 19 | 20 | ```json 21 | { 22 | "jsonrpc": "2.0", 23 | "id": "123", 24 | "method": "ping" 25 | } 26 | ``` 27 | 28 | ## Behavior Requirements 29 | 30 | 1. The receiver **MUST** respond promptly with an empty response: 31 | 32 | ```json 33 | { 34 | "jsonrpc": "2.0", 35 | "id": "123", 36 | "result": {} 37 | } 38 | ``` 39 | 40 | 2. If no response is received within a reasonable timeout period, the sender **MAY**: 41 | - Consider the connection stale 42 | - Terminate the connection 43 | - Attempt reconnection procedures 44 | 45 | ## Usage Patterns 46 | 47 | ```mermaid 48 | sequenceDiagram 49 | participant Sender 50 | participant Receiver 51 | 52 | Sender->>Receiver: ping request 53 | Receiver->>Sender: empty response 54 | ``` 55 | 56 | ## Implementation Considerations 57 | 58 | - Implementations **SHOULD** periodically issue pings to detect connection health 59 | - The frequency of pings **SHOULD** be configurable 60 | - Timeouts **SHOULD** be appropriate for the network environment 61 | - Excessive pinging **SHOULD** be avoided to reduce network overhead 62 | 63 | ## Error Handling 64 | 65 | - Timeouts **SHOULD** be treated as connection failures 66 | - Multiple failed pings **MAY** trigger connection reset 67 | - Implementations **SHOULD** log ping failures for diagnostics 68 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/basic/utilities/progress.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Progress 3 | weight: 30 4 | --- 5 | 6 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 7 | 8 | The Model Context Protocol (MCP) supports optional progress tracking for long-running 9 | operations through notification messages. Either side can send progress notifications to 10 | provide updates about operation status. 11 | 12 | ## Progress Flow 13 | 14 | When a party wants to _receive_ progress updates for a request, it includes a 15 | `progressToken` in the request metadata. 16 | 17 | - Progress tokens **MUST** be a string or integer value 18 | - Progress tokens can be chosen by the sender using any means, but **MUST** be unique 19 | across all active requests. 20 | 21 | ```json 22 | { 23 | "jsonrpc": "2.0", 24 | "id": 1, 25 | "method": "some_method", 26 | "params": { 27 | "_meta": { 28 | "progressToken": "abc123" 29 | } 30 | } 31 | } 32 | ``` 33 | 34 | The receiver **MAY** then send progress notifications containing: 35 | 36 | - The original progress token 37 | - The current progress value so far 38 | - An optional "total" value 39 | 40 | ```json 41 | { 42 | "jsonrpc": "2.0", 43 | "method": "notifications/progress", 44 | "params": { 45 | "progressToken": "abc123", 46 | "progress": 50, 47 | "total": 100 48 | } 49 | } 50 | ``` 51 | 52 | - The `progress` value **MUST** increase with each notification, even if the total is 53 | unknown. 54 | - The `progress` and the `total` values **MAY** be floating point. 55 | 56 | ## Behavior Requirements 57 | 58 | 1. Progress notifications **MUST** only reference tokens that: 59 | 60 | - Were provided in an active request 61 | - Are associated with an in-progress operation 62 | 63 | 2. Receivers of progress requests **MAY**: 64 | - Choose not to send any progress notifications 65 | - Send notifications at whatever frequency they deem appropriate 66 | - Omit the total value if unknown 67 | 68 | ```mermaid 69 | sequenceDiagram 70 | participant Sender 71 | participant Receiver 72 | 73 | Note over Sender,Receiver: Request with progress token 74 | Sender->>Receiver: Method request with progressToken 75 | 76 | Note over Sender,Receiver: Progress updates 77 | loop Progress Updates 78 | Receiver-->>Sender: Progress notification (0.2/1.0) 79 | Receiver-->>Sender: Progress notification (0.6/1.0) 80 | Receiver-->>Sender: Progress notification (1.0/1.0) 81 | end 82 | 83 | Note over Sender,Receiver: Operation complete 84 | Receiver->>Sender: Method response 85 | ``` 86 | 87 | ## Implementation Notes 88 | 89 | - Senders and receivers **SHOULD** track active progress tokens 90 | - Both parties **SHOULD** implement rate limiting to prevent flooding 91 | - Progress notifications **MUST** stop after completion 92 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/client/_index.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Client Features 3 | cascade: 4 | type: docs 5 | weight: 4 6 | --- 7 | 8 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 9 | 10 | Clients can implement additional features to enrich connected MCP servers: 11 | 12 | {{< cards >}} {{< card link="roots" title="Roots" icon="folder" >}} 13 | {{< card link="sampling" title="Sampling" icon="annotation" >}} {{< /cards >}} 14 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/client/roots.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Roots 3 | type: docs 4 | weight: 40 5 | --- 6 | 7 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 8 | 9 | The Model Context Protocol (MCP) provides a standardized way for clients to expose 10 | filesystem "roots" to servers. Roots define the boundaries of where servers can operate 11 | within the filesystem, allowing them to understand which directories and files they have 12 | access to. Servers can request the list of roots from supporting clients and receive 13 | notifications when that list changes. 14 | 15 | ## User Interaction Model 16 | 17 | Roots in MCP are typically exposed through workspace or project configuration interfaces. 18 | 19 | For example, implementations could offer a workspace/project picker that allows users to 20 | select directories and files the server should have access to. This can be combined with 21 | automatic workspace detection from version control systems or project files. 22 | 23 | However, implementations are free to expose roots through any interface pattern that 24 | suits their needs&mdash;the protocol itself does not mandate any specific user 25 | interaction model. 26 | 27 | ## Capabilities 28 | 29 | Clients that support roots **MUST** declare the `roots` capability during 30 | [initialization]({{< ref "/specification/2024-11-05/basic/lifecycle#initialization" >}}): 31 | 32 | ```json 33 | { 34 | "capabilities": { 35 | "roots": { 36 | "listChanged": true 37 | } 38 | } 39 | } 40 | ``` 41 | 42 | `listChanged` indicates whether the client will emit notifications when the list of roots 43 | changes. 44 | 45 | ## Protocol Messages 46 | 47 | ### Listing Roots 48 | 49 | To retrieve roots, servers send a `roots/list` request: 50 | 51 | **Request:** 52 | 53 | ```json 54 | { 55 | "jsonrpc": "2.0", 56 | "id": 1, 57 | "method": "roots/list" 58 | } 59 | ``` 60 | 61 | **Response:** 62 | 63 | ```json 64 | { 65 | "jsonrpc": "2.0", 66 | "id": 1, 67 | "result": { 68 | "roots": [ 69 | { 70 | "uri": "file:///home/user/projects/myproject", 71 | "name": "My Project" 72 | } 73 | ] 74 | } 75 | } 76 | ``` 77 | 78 | ### Root List Changes 79 | 80 | When roots change, clients that support `listChanged` **MUST** send a notification: 81 | 82 | ```json 83 | { 84 | "jsonrpc": "2.0", 85 | "method": "notifications/roots/list_changed" 86 | } 87 | ``` 88 | 89 | ## Message Flow 90 | 91 | ```mermaid 92 | sequenceDiagram 93 | participant Server 94 | participant Client 95 | 96 | Note over Server,Client: Discovery 97 | Server->>Client: roots/list 98 | Client-->>Server: Available roots 99 | 100 | Note over Server,Client: Changes 101 | Client--)Server: notifications/roots/list_changed 102 | Server->>Client: roots/list 103 | Client-->>Server: Updated roots 104 | ``` 105 | 106 | ## Data Types 107 | 108 | ### Root 109 | 110 | A root definition includes: 111 | 112 | - `uri`: Unique identifier for the root. This **MUST** be a `file://` URI in the current 113 | specification. 114 | - `name`: Optional human-readable name for display purposes. 115 | 116 | Example roots for different use cases: 117 | 118 | #### Project Directory 119 | 120 | ```json 121 | { 122 | "uri": "file:///home/user/projects/myproject", 123 | "name": "My Project" 124 | } 125 | ``` 126 | 127 | #### Multiple Repositories 128 | 129 | ```json 130 | [ 131 | { 132 | "uri": "file:///home/user/repos/frontend", 133 | "name": "Frontend Repository" 134 | }, 135 | { 136 | "uri": "file:///home/user/repos/backend", 137 | "name": "Backend Repository" 138 | } 139 | ] 140 | ``` 141 | 142 | ## Error Handling 143 | 144 | Clients **SHOULD** return standard JSON-RPC errors for common failure cases: 145 | 146 | - Client does not support roots: `-32601` (Method not found) 147 | - Internal errors: `-32603` 148 | 149 | Example error: 150 | 151 | ```json 152 | { 153 | "jsonrpc": "2.0", 154 | "id": 1, 155 | "error": { 156 | "code": -32601, 157 | "message": "Roots not supported", 158 | "data": { 159 | "reason": "Client does not have roots capability" 160 | } 161 | } 162 | } 163 | ``` 164 | 165 | ## Security Considerations 166 | 167 | 1. Clients **MUST**: 168 | 169 | - Only expose roots with appropriate permissions 170 | - Validate all root URIs to prevent path traversal 171 | - Implement proper access controls 172 | - Monitor root accessibility 173 | 174 | 2. Servers **SHOULD**: 175 | - Handle cases where roots become unavailable 176 | - Respect root boundaries during operations 177 | - Validate all paths against provided roots 178 | 179 | ## Implementation Guidelines 180 | 181 | 1. Clients **SHOULD**: 182 | 183 | - Prompt users for consent before exposing roots to servers 184 | - Provide clear user interfaces for root management 185 | - Validate root accessibility before exposing 186 | - Monitor for root changes 187 | 188 | 2. Servers **SHOULD**: 189 | - Check for roots capability before usage 190 | - Handle root list changes gracefully 191 | - Respect root boundaries in operations 192 | - Cache root information appropriately 193 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/client/sampling.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Sampling 3 | type: docs 4 | weight: 40 5 | --- 6 | 7 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 8 | 9 | The Model Context Protocol (MCP) provides a standardized way for servers to request LLM 10 | sampling ("completions" or "generations") from language models via clients. This flow 11 | allows clients to maintain control over model access, selection, and permissions while 12 | enabling servers to leverage AI capabilities&mdash;with no server API keys necessary. 13 | Servers can request text or image-based interactions and optionally include context from 14 | MCP servers in their prompts. 15 | 16 | ## User Interaction Model 17 | 18 | Sampling in MCP allows servers to implement agentic behaviors, by enabling LLM calls to 19 | occur _nested_ inside other MCP server features. 20 | 21 | Implementations are free to expose sampling through any interface pattern that suits 22 | their needs&mdash;the protocol itself does not mandate any specific user interaction 23 | model. 24 | 25 | {{< callout type="warning" >}} For trust & safety and security, there **SHOULD** always 26 | be a human in the loop with the ability to deny sampling requests. 27 | 28 | Applications **SHOULD**: 29 | 30 | - Provide UI that makes it easy and intuitive to review sampling requests 31 | - Allow users to view and edit prompts before sending 32 | - Present generated responses for review before delivery {{< /callout >}} 33 | 34 | ## Capabilities 35 | 36 | Clients that support sampling **MUST** declare the `sampling` capability during 37 | [initialization]({{< ref "/specification/2024-11-05/basic/lifecycle#initialization" >}}): 38 | 39 | ```json 40 | { 41 | "capabilities": { 42 | "sampling": {} 43 | } 44 | } 45 | ``` 46 | 47 | ## Protocol Messages 48 | 49 | ### Creating Messages 50 | 51 | To request a language model generation, servers send a `sampling/createMessage` request: 52 | 53 | **Request:** 54 | 55 | ```json 56 | { 57 | "jsonrpc": "2.0", 58 | "id": 1, 59 | "method": "sampling/createMessage", 60 | "params": { 61 | "messages": [ 62 | { 63 | "role": "user", 64 | "content": { 65 | "type": "text", 66 | "text": "What is the capital of France?" 67 | } 68 | } 69 | ], 70 | "modelPreferences": { 71 | "hints": [ 72 | { 73 | "name": "claude-3-sonnet" 74 | } 75 | ], 76 | "intelligencePriority": 0.8, 77 | "speedPriority": 0.5 78 | }, 79 | "systemPrompt": "You are a helpful assistant.", 80 | "maxTokens": 100 81 | } 82 | } 83 | ``` 84 | 85 | **Response:** 86 | 87 | ```json 88 | { 89 | "jsonrpc": "2.0", 90 | "id": 1, 91 | "result": { 92 | "role": "assistant", 93 | "content": { 94 | "type": "text", 95 | "text": "The capital of France is Paris." 96 | }, 97 | "model": "claude-3-sonnet-20240307", 98 | "stopReason": "endTurn" 99 | } 100 | } 101 | ``` 102 | 103 | ## Message Flow 104 | 105 | ```mermaid 106 | sequenceDiagram 107 | participant Server 108 | participant Client 109 | participant User 110 | participant LLM 111 | 112 | Note over Server,Client: Server initiates sampling 113 | Server->>Client: sampling/createMessage 114 | 115 | Note over Client,User: Human-in-the-loop review 116 | Client->>User: Present request for approval 117 | User-->>Client: Review and approve/modify 118 | 119 | Note over Client,LLM: Model interaction 120 | Client->>LLM: Forward approved request 121 | LLM-->>Client: Return generation 122 | 123 | Note over Client,User: Response review 124 | Client->>User: Present response for approval 125 | User-->>Client: Review and approve/modify 126 | 127 | Note over Server,Client: Complete request 128 | Client-->>Server: Return approved response 129 | ``` 130 | 131 | ## Data Types 132 | 133 | ### Messages 134 | 135 | Sampling messages can contain: 136 | 137 | #### Text Content 138 | 139 | ```json 140 | { 141 | "type": "text", 142 | "text": "The message content" 143 | } 144 | ``` 145 | 146 | #### Image Content 147 | 148 | ```json 149 | { 150 | "type": "image", 151 | "data": "base64-encoded-image-data", 152 | "mimeType": "image/jpeg" 153 | } 154 | ``` 155 | 156 | ### Model Preferences 157 | 158 | Model selection in MCP requires careful abstraction since servers and clients may use 159 | different AI providers with distinct model offerings. A server cannot simply request a 160 | specific model by name since the client may not have access to that exact model or may 161 | prefer to use a different provider's equivalent model. 162 | 163 | To solve this, MCP implements a preference system that combines abstract capability 164 | priorities with optional model hints: 165 | 166 | #### Capability Priorities 167 | 168 | Servers express their needs through three normalized priority values (0-1): 169 | 170 | - `costPriority`: How important is minimizing costs? Higher values prefer cheaper models. 171 | - `speedPriority`: How important is low latency? Higher values prefer faster models. 172 | - `intelligencePriority`: How important are advanced capabilities? Higher values prefer 173 | more capable models. 174 | 175 | #### Model Hints 176 | 177 | While priorities help select models based on characteristics, `hints` allow servers to 178 | suggest specific models or model families: 179 | 180 | - Hints are treated as substrings that can match model names flexibly 181 | - Multiple hints are evaluated in order of preference 182 | - Clients **MAY** map hints to equivalent models from different providers 183 | - Hints are advisory&mdash;clients make final model selection 184 | 185 | For example: 186 | 187 | ```json 188 | { 189 | "hints": [ 190 | { "name": "claude-3-sonnet" }, // Prefer Sonnet-class models 191 | { "name": "claude" } // Fall back to any Claude model 192 | ], 193 | "costPriority": 0.3, // Cost is less important 194 | "speedPriority": 0.8, // Speed is very important 195 | "intelligencePriority": 0.5 // Moderate capability needs 196 | } 197 | ``` 198 | 199 | The client processes these preferences to select an appropriate model from its available 200 | options. For instance, if the client doesn't have access to Claude models but has Gemini, 201 | it might map the sonnet hint to `gemini-1.5-pro` based on similar capabilities. 202 | 203 | ## Error Handling 204 | 205 | Clients **SHOULD** return errors for common failure cases: 206 | 207 | Example error: 208 | 209 | ```json 210 | { 211 | "jsonrpc": "2.0", 212 | "id": 1, 213 | "error": { 214 | "code": -1, 215 | "message": "User rejected sampling request" 216 | } 217 | } 218 | ``` 219 | 220 | ## Security Considerations 221 | 222 | 1. Clients **SHOULD** implement user approval controls 223 | 2. Both parties **SHOULD** validate message content 224 | 3. Clients **SHOULD** respect model preference hints 225 | 4. Clients **SHOULD** implement rate limiting 226 | 5. Both parties **MUST** handle sensitive data appropriately 227 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/server/_index.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Server Features 3 | cascade: 4 | type: docs 5 | weight: 3 6 | --- 7 | 8 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 9 | 10 | Servers provide the fundamental building blocks for adding context to language models via 11 | MCP. These primitives enable rich interactions between clients, servers, and language 12 | models: 13 | 14 | - **Prompts**: Pre-defined templates or instructions that guide language model 15 | interactions 16 | - **Resources**: Structured data or content that provides additional context to the model 17 | - **Tools**: Executable functions that allow models to perform actions or retrieve 18 | information 19 | 20 | Each primitive can be summarized in the following control hierarchy: 21 | 22 | | Primitive | Control | Description | Example | 23 | | --------- | ---------------------- | -------------------------------------------------- | ------------------------------- | 24 | | Prompts | User-controlled | Interactive templates invoked by user choice | Slash commands, menu options | 25 | | Resources | Application-controlled | Contextual data attached and managed by the client | File contents, git history | 26 | | Tools | Model-controlled | Functions exposed to the LLM to take actions | API POST requests, file writing | 27 | 28 | Explore these key primitives in more detail below: 29 | 30 | {{< cards >}} {{< card link="prompts" title="Prompts" icon="chat-alt-2" >}} 31 | {{< card link="resources" title="Resources" icon="document" >}} 32 | {{< card link="tools" title="Tools" icon="adjustments" >}} {{< /cards >}} 33 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/server/prompts.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Prompts 3 | weight: 10 4 | --- 5 | 6 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 7 | 8 | The Model Context Protocol (MCP) provides a standardized way for servers to expose prompt 9 | templates to clients. Prompts allow servers to provide structured messages and 10 | instructions for interacting with language models. Clients can discover available 11 | prompts, retrieve their contents, and provide arguments to customize them. 12 | 13 | ## User Interaction Model 14 | 15 | Prompts are designed to be **user-controlled**, meaning they are exposed from servers to 16 | clients with the intention of the user being able to explicitly select them for use. 17 | 18 | Typically, prompts would be triggered through user-initiated commands in the user 19 | interface, which allows users to naturally discover and invoke available prompts. 20 | 21 | For example, as slash commands: 22 | 23 | ![Example of prompt exposed as slash command](slash-command.png) 24 | 25 | However, implementors are free to expose prompts through any interface pattern that suits 26 | their needs&mdash;the protocol itself does not mandate any specific user interaction 27 | model. 28 | 29 | ## Capabilities 30 | 31 | Servers that support prompts **MUST** declare the `prompts` capability during 32 | [initialization]({{< ref "/specification/2024-11-05/basic/lifecycle#initialization" >}}): 33 | 34 | ```json 35 | { 36 | "capabilities": { 37 | "prompts": { 38 | "listChanged": true 39 | } 40 | } 41 | } 42 | ``` 43 | 44 | `listChanged` indicates whether the server will emit notifications when the list of 45 | available prompts changes. 46 | 47 | ## Protocol Messages 48 | 49 | ### Listing Prompts 50 | 51 | To retrieve available prompts, clients send a `prompts/list` request. This operation 52 | supports 53 | [pagination]({{< ref "/specification/2024-11-05/server/utilities/pagination" >}}). 54 | 55 | **Request:** 56 | 57 | ```json 58 | { 59 | "jsonrpc": "2.0", 60 | "id": 1, 61 | "method": "prompts/list", 62 | "params": { 63 | "cursor": "optional-cursor-value" 64 | } 65 | } 66 | ``` 67 | 68 | **Response:** 69 | 70 | ```json 71 | { 72 | "jsonrpc": "2.0", 73 | "id": 1, 74 | "result": { 75 | "prompts": [ 76 | { 77 | "name": "code_review", 78 | "description": "Asks the LLM to analyze code quality and suggest improvements", 79 | "arguments": [ 80 | { 81 | "name": "code", 82 | "description": "The code to review", 83 | "required": true 84 | } 85 | ] 86 | } 87 | ], 88 | "nextCursor": "next-page-cursor" 89 | } 90 | } 91 | ``` 92 | 93 | ### Getting a Prompt 94 | 95 | To retrieve a specific prompt, clients send a `prompts/get` request. Arguments may be 96 | auto-completed through [the completion 97 | API]({{< ref "/specification/2024-11-05/server/utilities/completion" >}}). 98 | 99 | **Request:** 100 | 101 | ```json 102 | { 103 | "jsonrpc": "2.0", 104 | "id": 2, 105 | "method": "prompts/get", 106 | "params": { 107 | "name": "code_review", 108 | "arguments": { 109 | "code": "def hello():\n print('world')" 110 | } 111 | } 112 | } 113 | ``` 114 | 115 | **Response:** 116 | 117 | ```json 118 | { 119 | "jsonrpc": "2.0", 120 | "id": 2, 121 | "result": { 122 | "description": "Code review prompt", 123 | "messages": [ 124 | { 125 | "role": "user", 126 | "content": { 127 | "type": "text", 128 | "text": "Please review this Python code:\ndef hello():\n print('world')" 129 | } 130 | } 131 | ] 132 | } 133 | } 134 | ``` 135 | 136 | ### List Changed Notification 137 | 138 | When the list of available prompts changes, servers that declared the `listChanged` 139 | capability **SHOULD** send a notification: 140 | 141 | ```json 142 | { 143 | "jsonrpc": "2.0", 144 | "method": "notifications/prompts/list_changed" 145 | } 146 | ``` 147 | 148 | ## Message Flow 149 | 150 | ```mermaid 151 | sequenceDiagram 152 | participant Client 153 | participant Server 154 | 155 | Note over Client,Server: Discovery 156 | Client->>Server: prompts/list 157 | Server-->>Client: List of prompts 158 | 159 | Note over Client,Server: Usage 160 | Client->>Server: prompts/get 161 | Server-->>Client: Prompt content 162 | 163 | opt listChanged 164 | Note over Client,Server: Changes 165 | Server--)Client: prompts/list_changed 166 | Client->>Server: prompts/list 167 | Server-->>Client: Updated prompts 168 | end 169 | ``` 170 | 171 | ## Data Types 172 | 173 | ### Prompt 174 | 175 | A prompt definition includes: 176 | 177 | - `name`: Unique identifier for the prompt 178 | - `description`: Optional human-readable description 179 | - `arguments`: Optional list of arguments for customization 180 | 181 | ### PromptMessage 182 | 183 | Messages in a prompt can contain: 184 | 185 | - `role`: Either "user" or "assistant" to indicate the speaker 186 | - `content`: One of the following content types: 187 | 188 | #### Text Content 189 | 190 | Text content represents plain text messages: 191 | 192 | ```json 193 | { 194 | "type": "text", 195 | "text": "The text content of the message" 196 | } 197 | ``` 198 | 199 | This is the most common content type used for natural language interactions. 200 | 201 | #### Image Content 202 | 203 | Image content allows including visual information in messages: 204 | 205 | ```json 206 | { 207 | "type": "image", 208 | "data": "base64-encoded-image-data", 209 | "mimeType": "image/png" 210 | } 211 | ``` 212 | 213 | The image data **MUST** be base64-encoded and include a valid MIME type. This enables 214 | multi-modal interactions where visual context is important. 215 | 216 | #### Embedded Resources 217 | 218 | Embedded resources allow referencing server-side resources directly in messages: 219 | 220 | ```json 221 | { 222 | "type": "resource", 223 | "resource": { 224 | "uri": "resource://example", 225 | "mimeType": "text/plain", 226 | "text": "Resource content" 227 | } 228 | } 229 | ``` 230 | 231 | Resources can contain either text or binary (blob) data and **MUST** include: 232 | 233 | - A valid resource URI 234 | - The appropriate MIME type 235 | - Either text content or base64-encoded blob data 236 | 237 | Embedded resources enable prompts to seamlessly incorporate server-managed content like 238 | documentation, code samples, or other reference materials directly into the conversation 239 | flow. 240 | 241 | ## Error Handling 242 | 243 | Servers **SHOULD** return standard JSON-RPC errors for common failure cases: 244 | 245 | - Invalid prompt name: `-32602` (Invalid params) 246 | - Missing required arguments: `-32602` (Invalid params) 247 | - Internal errors: `-32603` (Internal error) 248 | 249 | ## Implementation Considerations 250 | 251 | 1. Servers **SHOULD** validate prompt arguments before processing 252 | 2. Clients **SHOULD** handle pagination for large prompt lists 253 | 3. Both parties **SHOULD** respect capability negotiation 254 | 255 | ## Security 256 | 257 | Implementations **MUST** carefully validate all prompt inputs and outputs to prevent 258 | injection attacks or unauthorized access to resources. 259 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/server/resource-picker.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/modelcontextprotocol/specification/main/docs/specification/2024-11-05/server/resource-picker.png -------------------------------------------------------------------------------- /docs/specification/2024-11-05/server/resources.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Resources 3 | type: docs 4 | weight: 20 5 | --- 6 | 7 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 8 | 9 | The Model Context Protocol (MCP) provides a standardized way for servers to expose 10 | resources to clients. Resources allow servers to share data that provides context to 11 | language models, such as files, database schemas, or application-specific information. 12 | Each resource is uniquely identified by a 13 | [URI](https://datatracker.ietf.org/doc/html/rfc3986). 14 | 15 | ## User Interaction Model 16 | 17 | Resources in MCP are designed to be **application-driven**, with host applications 18 | determining how to incorporate context based on their needs. 19 | 20 | For example, applications could: 21 | 22 | - Expose resources through UI elements for explicit selection, in a tree or list view 23 | - Allow the user to search through and filter available resources 24 | - Implement automatic context inclusion, based on heuristics or the AI model's selection 25 | 26 | ![Example of resource context picker](resource-picker.png) 27 | 28 | However, implementations are free to expose resources through any interface pattern that 29 | suits their needs&mdash;the protocol itself does not mandate any specific user 30 | interaction model. 31 | 32 | ## Capabilities 33 | 34 | Servers that support resources **MUST** declare the `resources` capability: 35 | 36 | ```json 37 | { 38 | "capabilities": { 39 | "resources": { 40 | "subscribe": true, 41 | "listChanged": true 42 | } 43 | } 44 | } 45 | ``` 46 | 47 | The capability supports two optional features: 48 | 49 | - `subscribe`: whether the client can subscribe to be notified of changes to individual 50 | resources. 51 | - `listChanged`: whether the server will emit notifications when the list of available 52 | resources changes. 53 | 54 | Both `subscribe` and `listChanged` are optional&mdash;servers can support neither, 55 | either, or both: 56 | 57 | ```json 58 | { 59 | "capabilities": { 60 | "resources": {} // Neither feature supported 61 | } 62 | } 63 | ``` 64 | 65 | ```json 66 | { 67 | "capabilities": { 68 | "resources": { 69 | "subscribe": true // Only subscriptions supported 70 | } 71 | } 72 | } 73 | ``` 74 | 75 | ```json 76 | { 77 | "capabilities": { 78 | "resources": { 79 | "listChanged": true // Only list change notifications supported 80 | } 81 | } 82 | } 83 | ``` 84 | 85 | ## Protocol Messages 86 | 87 | ### Listing Resources 88 | 89 | To discover available resources, clients send a `resources/list` request. This operation 90 | supports 91 | [pagination]({{< ref "/specification/2024-11-05/server/utilities/pagination" >}}). 92 | 93 | **Request:** 94 | 95 | ```json 96 | { 97 | "jsonrpc": "2.0", 98 | "id": 1, 99 | "method": "resources/list", 100 | "params": { 101 | "cursor": "optional-cursor-value" 102 | } 103 | } 104 | ``` 105 | 106 | **Response:** 107 | 108 | ```json 109 | { 110 | "jsonrpc": "2.0", 111 | "id": 1, 112 | "result": { 113 | "resources": [ 114 | { 115 | "uri": "file:///project/src/main.rs", 116 | "name": "main.rs", 117 | "description": "Primary application entry point", 118 | "mimeType": "text/x-rust" 119 | } 120 | ], 121 | "nextCursor": "next-page-cursor" 122 | } 123 | } 124 | ``` 125 | 126 | ### Reading Resources 127 | 128 | To retrieve resource contents, clients send a `resources/read` request: 129 | 130 | **Request:** 131 | 132 | ```json 133 | { 134 | "jsonrpc": "2.0", 135 | "id": 2, 136 | "method": "resources/read", 137 | "params": { 138 | "uri": "file:///project/src/main.rs" 139 | } 140 | } 141 | ``` 142 | 143 | **Response:** 144 | 145 | ```json 146 | { 147 | "jsonrpc": "2.0", 148 | "id": 2, 149 | "result": { 150 | "contents": [ 151 | { 152 | "uri": "file:///project/src/main.rs", 153 | "mimeType": "text/x-rust", 154 | "text": "fn main() {\n println!(\"Hello world!\");\n}" 155 | } 156 | ] 157 | } 158 | } 159 | ``` 160 | 161 | ### Resource Templates 162 | 163 | Resource templates allow servers to expose parameterized resources using 164 | [URI templates](https://datatracker.ietf.org/doc/html/rfc6570). Arguments may be 165 | auto-completed through [the completion 166 | API]({{< ref "/specification/2024-11-05/server/utilities/completion" >}}). 167 | 168 | **Request:** 169 | 170 | ```json 171 | { 172 | "jsonrpc": "2.0", 173 | "id": 3, 174 | "method": "resources/templates/list" 175 | } 176 | ``` 177 | 178 | **Response:** 179 | 180 | ```json 181 | { 182 | "jsonrpc": "2.0", 183 | "id": 3, 184 | "result": { 185 | "resourceTemplates": [ 186 | { 187 | "uriTemplate": "file:///{path}", 188 | "name": "Project Files", 189 | "description": "Access files in the project directory", 190 | "mimeType": "application/octet-stream" 191 | } 192 | ] 193 | } 194 | } 195 | ``` 196 | 197 | ### List Changed Notification 198 | 199 | When the list of available resources changes, servers that declared the `listChanged` 200 | capability **SHOULD** send a notification: 201 | 202 | ```json 203 | { 204 | "jsonrpc": "2.0", 205 | "method": "notifications/resources/list_changed" 206 | } 207 | ``` 208 | 209 | ### Subscriptions 210 | 211 | The protocol supports optional subscriptions to resource changes. Clients can subscribe 212 | to specific resources and receive notifications when they change: 213 | 214 | **Subscribe Request:** 215 | 216 | ```json 217 | { 218 | "jsonrpc": "2.0", 219 | "id": 4, 220 | "method": "resources/subscribe", 221 | "params": { 222 | "uri": "file:///project/src/main.rs" 223 | } 224 | } 225 | ``` 226 | 227 | **Update Notification:** 228 | 229 | ```json 230 | { 231 | "jsonrpc": "2.0", 232 | "method": "notifications/resources/updated", 233 | "params": { 234 | "uri": "file:///project/src/main.rs" 235 | } 236 | } 237 | ``` 238 | 239 | ## Message Flow 240 | 241 | ```mermaid 242 | sequenceDiagram 243 | participant Client 244 | participant Server 245 | 246 | Note over Client,Server: Resource Discovery 247 | Client->>Server: resources/list 248 | Server-->>Client: List of resources 249 | 250 | Note over Client,Server: Resource Access 251 | Client->>Server: resources/read 252 | Server-->>Client: Resource contents 253 | 254 | Note over Client,Server: Subscriptions 255 | Client->>Server: resources/subscribe 256 | Server-->>Client: Subscription confirmed 257 | 258 | Note over Client,Server: Updates 259 | Server--)Client: notifications/resources/updated 260 | Client->>Server: resources/read 261 | Server-->>Client: Updated contents 262 | ``` 263 | 264 | ## Data Types 265 | 266 | ### Resource 267 | 268 | A resource definition includes: 269 | 270 | - `uri`: Unique identifier for the resource 271 | - `name`: Human-readable name 272 | - `description`: Optional description 273 | - `mimeType`: Optional MIME type 274 | 275 | ### Resource Contents 276 | 277 | Resources can contain either text or binary data: 278 | 279 | #### Text Content 280 | 281 | ```json 282 | { 283 | "uri": "file:///example.txt", 284 | "mimeType": "text/plain", 285 | "text": "Resource content" 286 | } 287 | ``` 288 | 289 | #### Binary Content 290 | 291 | ```json 292 | { 293 | "uri": "file:///example.png", 294 | "mimeType": "image/png", 295 | "blob": "base64-encoded-data" 296 | } 297 | ``` 298 | 299 | ## Common URI Schemes 300 | 301 | The protocol defines several standard URI schemes. This list not 302 | exhaustive&mdash;implementations are always free to use additional, custom URI schemes. 303 | 304 | ### https:// 305 | 306 | Used to represent a resource available on the web. 307 | 308 | Servers **SHOULD** use this scheme only when the client is able to fetch and load the 309 | resource directly from the web on its own—that is, it doesn’t need to read the resource 310 | via the MCP server. 311 | 312 | For other use cases, servers **SHOULD** prefer to use another URI scheme, or define a 313 | custom one, even if the server will itself be downloading resource contents over the 314 | internet. 315 | 316 | ### file:// 317 | 318 | Used to identify resources that behave like a filesystem. However, the resources do not 319 | need to map to an actual physical filesystem. 320 | 321 | MCP servers **MAY** identify file:// resources with an 322 | [XDG MIME type](https://specifications.freedesktop.org/shared-mime-info-spec/0.14/ar01s02.html#id-1.3.14), 323 | like `inode/directory`, to represent non-regular files (such as directories) that don’t 324 | otherwise have a standard MIME type. 325 | 326 | ### git:// 327 | 328 | Git version control integration. 329 | 330 | ## Error Handling 331 | 332 | Servers **SHOULD** return standard JSON-RPC errors for common failure cases: 333 | 334 | - Resource not found: `-32002` 335 | - Internal errors: `-32603` 336 | 337 | Example error: 338 | 339 | ```json 340 | { 341 | "jsonrpc": "2.0", 342 | "id": 5, 343 | "error": { 344 | "code": -32002, 345 | "message": "Resource not found", 346 | "data": { 347 | "uri": "file:///nonexistent.txt" 348 | } 349 | } 350 | } 351 | ``` 352 | 353 | ## Security Considerations 354 | 355 | 1. Servers **MUST** validate all resource URIs 356 | 2. Access controls **SHOULD** be implemented for sensitive resources 357 | 3. Binary data **MUST** be properly encoded 358 | 4. Resource permissions **SHOULD** be checked before operations 359 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/server/slash-command.png: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/modelcontextprotocol/specification/main/docs/specification/2024-11-05/server/slash-command.png -------------------------------------------------------------------------------- /docs/specification/2024-11-05/server/tools.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Tools 3 | type: docs 4 | weight: 40 5 | --- 6 | 7 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 8 | 9 | The Model Context Protocol (MCP) allows servers to expose tools that can be invoked by 10 | language models. Tools enable models to interact with external systems, such as querying 11 | databases, calling APIs, or performing computations. Each tool is uniquely identified by 12 | a name and includes metadata describing its schema. 13 | 14 | ## User Interaction Model 15 | 16 | Tools in MCP are designed to be **model-controlled**, meaning that the language model can 17 | discover and invoke tools automatically based on its contextual understanding and the 18 | user's prompts. 19 | 20 | However, implementations are free to expose tools through any interface pattern that 21 | suits their needs&mdash;the protocol itself does not mandate any specific user 22 | interaction model. 23 | 24 | {{< callout type="warning" >}} For trust & safety and security, there **SHOULD** always 25 | be a human in the loop with the ability to deny tool invocations. 26 | 27 | Applications **SHOULD**: 28 | 29 | - Provide UI that makes clear which tools are being exposed to the AI model 30 | - Insert clear visual indicators when tools are invoked 31 | - Present confirmation prompts to the user for operations, to ensure a human is in the 32 | loop {{< /callout >}} 33 | 34 | ## Capabilities 35 | 36 | Servers that support tools **MUST** declare the `tools` capability: 37 | 38 | ```json 39 | { 40 | "capabilities": { 41 | "tools": { 42 | "listChanged": true 43 | } 44 | } 45 | } 46 | ``` 47 | 48 | `listChanged` indicates whether the server will emit notifications when the list of 49 | available tools changes. 50 | 51 | ## Protocol Messages 52 | 53 | ### Listing Tools 54 | 55 | To discover available tools, clients send a `tools/list` request. This operation supports 56 | [pagination]({{< ref "/specification/2024-11-05/server/utilities/pagination" >}}). 57 | 58 | **Request:** 59 | 60 | ```json 61 | { 62 | "jsonrpc": "2.0", 63 | "id": 1, 64 | "method": "tools/list", 65 | "params": { 66 | "cursor": "optional-cursor-value" 67 | } 68 | } 69 | ``` 70 | 71 | **Response:** 72 | 73 | ```json 74 | { 75 | "jsonrpc": "2.0", 76 | "id": 1, 77 | "result": { 78 | "tools": [ 79 | { 80 | "name": "get_weather", 81 | "description": "Get current weather information for a location", 82 | "inputSchema": { 83 | "type": "object", 84 | "properties": { 85 | "location": { 86 | "type": "string", 87 | "description": "City name or zip code" 88 | } 89 | }, 90 | "required": ["location"] 91 | } 92 | } 93 | ], 94 | "nextCursor": "next-page-cursor" 95 | } 96 | } 97 | ``` 98 | 99 | ### Calling Tools 100 | 101 | To invoke a tool, clients send a `tools/call` request: 102 | 103 | **Request:** 104 | 105 | ```json 106 | { 107 | "jsonrpc": "2.0", 108 | "id": 2, 109 | "method": "tools/call", 110 | "params": { 111 | "name": "get_weather", 112 | "arguments": { 113 | "location": "New York" 114 | } 115 | } 116 | } 117 | ``` 118 | 119 | **Response:** 120 | 121 | ```json 122 | { 123 | "jsonrpc": "2.0", 124 | "id": 2, 125 | "result": { 126 | "content": [ 127 | { 128 | "type": "text", 129 | "text": "Current weather in New York:\nTemperature: 72°F\nConditions: Partly cloudy" 130 | } 131 | ], 132 | "isError": false 133 | } 134 | } 135 | ``` 136 | 137 | ### List Changed Notification 138 | 139 | When the list of available tools changes, servers that declared the `listChanged` 140 | capability **SHOULD** send a notification: 141 | 142 | ```json 143 | { 144 | "jsonrpc": "2.0", 145 | "method": "notifications/tools/list_changed" 146 | } 147 | ``` 148 | 149 | ## Message Flow 150 | 151 | ```mermaid 152 | sequenceDiagram 153 | participant LLM 154 | participant Client 155 | participant Server 156 | 157 | Note over Client,Server: Discovery 158 | Client->>Server: tools/list 159 | Server-->>Client: List of tools 160 | 161 | Note over Client,LLM: Tool Selection 162 | LLM->>Client: Select tool to use 163 | 164 | Note over Client,Server: Invocation 165 | Client->>Server: tools/call 166 | Server-->>Client: Tool result 167 | Client->>LLM: Process result 168 | 169 | Note over Client,Server: Updates 170 | Server--)Client: tools/list_changed 171 | Client->>Server: tools/list 172 | Server-->>Client: Updated tools 173 | ``` 174 | 175 | ## Data Types 176 | 177 | ### Tool 178 | 179 | A tool definition includes: 180 | 181 | - `name`: Unique identifier for the tool 182 | - `description`: Human-readable description of functionality 183 | - `inputSchema`: JSON Schema defining expected parameters 184 | 185 | ### Tool Result 186 | 187 | Tool results can contain multiple content items of different types: 188 | 189 | #### Text Content 190 | 191 | ```json 192 | { 193 | "type": "text", 194 | "text": "Tool result text" 195 | } 196 | ``` 197 | 198 | #### Image Content 199 | 200 | ```json 201 | { 202 | "type": "image", 203 | "data": "base64-encoded-data", 204 | "mimeType": "image/png" 205 | } 206 | ``` 207 | 208 | #### Embedded Resources 209 | 210 | [Resources]({{< ref "/specification/2024-11-05/server/resources" >}}) **MAY** be 211 | embedded, to provide additional context or data, behind a URI that can be subscribed to 212 | or fetched again by the client later: 213 | 214 | ```json 215 | { 216 | "type": "resource", 217 | "resource": { 218 | "uri": "resource://example", 219 | "mimeType": "text/plain", 220 | "text": "Resource content" 221 | } 222 | } 223 | ``` 224 | 225 | ## Error Handling 226 | 227 | Tools use two error reporting mechanisms: 228 | 229 | 1. **Protocol Errors**: Standard JSON-RPC errors for issues like: 230 | 231 | - Unknown tools 232 | - Invalid arguments 233 | - Server errors 234 | 235 | 2. **Tool Execution Errors**: Reported in tool results with `isError: true`: 236 | - API failures 237 | - Invalid input data 238 | - Business logic errors 239 | 240 | Example protocol error: 241 | 242 | ```json 243 | { 244 | "jsonrpc": "2.0", 245 | "id": 3, 246 | "error": { 247 | "code": -32602, 248 | "message": "Unknown tool: invalid_tool_name" 249 | } 250 | } 251 | ``` 252 | 253 | Example tool execution error: 254 | 255 | ```json 256 | { 257 | "jsonrpc": "2.0", 258 | "id": 4, 259 | "result": { 260 | "content": [ 261 | { 262 | "type": "text", 263 | "text": "Failed to fetch weather data: API rate limit exceeded" 264 | } 265 | ], 266 | "isError": true 267 | } 268 | } 269 | ``` 270 | 271 | ## Security Considerations 272 | 273 | 1. Servers **MUST**: 274 | 275 | - Validate all tool inputs 276 | - Implement proper access controls 277 | - Rate limit tool invocations 278 | - Sanitize tool outputs 279 | 280 | 2. Clients **SHOULD**: 281 | - Prompt for user confirmation on sensitive operations 282 | - Show tool inputs to the user before calling the server, to avoid malicious or 283 | accidental data exfiltration 284 | - Validate tool results before passing to LLM 285 | - Implement timeouts for tool calls 286 | - Log tool usage for audit purposes 287 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/server/utilities/_index.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Utilities 3 | --- 4 | 5 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 6 | 7 | These optional features can be used to enhance server functionality. 8 | 9 | {{< cards >}} {{< card link="completion" title="Completion" icon="at-symbol" >}} 10 | {{< card link="logging" title="Logging" icon="terminal" >}} 11 | {{< card link="pagination" title="Pagination" icon="collection" >}} {{< /cards >}} 12 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/server/utilities/completion.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Completion 3 | --- 4 | 5 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 6 | 7 | The Model Context Protocol (MCP) provides a standardized way for servers to offer 8 | argument autocompletion suggestions for prompts and resource URIs. This enables rich, 9 | IDE-like experiences where users receive contextual suggestions while entering argument 10 | values. 11 | 12 | ## User Interaction Model 13 | 14 | Completion in MCP is designed to support interactive user experiences similar to IDE code 15 | completion. 16 | 17 | For example, applications may show completion suggestions in a dropdown or popup menu as 18 | users type, with the ability to filter and select from available options. 19 | 20 | However, implementations are free to expose completion through any interface pattern that 21 | suits their needs&mdash;the protocol itself does not mandate any specific user 22 | interaction model. 23 | 24 | ## Protocol Messages 25 | 26 | ### Requesting Completions 27 | 28 | To get completion suggestions, clients send a `completion/complete` request specifying 29 | what is being completed through a reference type: 30 | 31 | **Request:** 32 | 33 | ```json 34 | { 35 | "jsonrpc": "2.0", 36 | "id": 1, 37 | "method": "completion/complete", 38 | "params": { 39 | "ref": { 40 | "type": "ref/prompt", 41 | "name": "code_review" 42 | }, 43 | "argument": { 44 | "name": "language", 45 | "value": "py" 46 | } 47 | } 48 | } 49 | ``` 50 | 51 | **Response:** 52 | 53 | ```json 54 | { 55 | "jsonrpc": "2.0", 56 | "id": 1, 57 | "result": { 58 | "completion": { 59 | "values": ["python", "pytorch", "pyside"], 60 | "total": 10, 61 | "hasMore": true 62 | } 63 | } 64 | } 65 | ``` 66 | 67 | ### Reference Types 68 | 69 | The protocol supports two types of completion references: 70 | 71 | | Type | Description | Example | 72 | | -------------- | --------------------------- | --------------------------------------------------- | 73 | | `ref/prompt` | References a prompt by name | `{"type": "ref/prompt", "name": "code_review"}` | 74 | | `ref/resource` | References a resource URI | `{"type": "ref/resource", "uri": "file:///{path}"}` | 75 | 76 | ### Completion Results 77 | 78 | Servers return an array of completion values ranked by relevance, with: 79 | 80 | - Maximum 100 items per response 81 | - Optional total number of available matches 82 | - Boolean indicating if additional results exist 83 | 84 | ## Message Flow 85 | 86 | ```mermaid 87 | sequenceDiagram 88 | participant Client 89 | participant Server 90 | 91 | Note over Client: User types argument 92 | Client->>Server: completion/complete 93 | Server-->>Client: Completion suggestions 94 | 95 | Note over Client: User continues typing 96 | Client->>Server: completion/complete 97 | Server-->>Client: Refined suggestions 98 | ``` 99 | 100 | ## Data Types 101 | 102 | ### CompleteRequest 103 | 104 | - `ref`: A `PromptReference` or `ResourceReference` 105 | - `argument`: Object containing: 106 | - `name`: Argument name 107 | - `value`: Current value 108 | 109 | ### CompleteResult 110 | 111 | - `completion`: Object containing: 112 | - `values`: Array of suggestions (max 100) 113 | - `total`: Optional total matches 114 | - `hasMore`: Additional results flag 115 | 116 | ## Implementation Considerations 117 | 118 | 1. Servers **SHOULD**: 119 | 120 | - Return suggestions sorted by relevance 121 | - Implement fuzzy matching where appropriate 122 | - Rate limit completion requests 123 | - Validate all inputs 124 | 125 | 2. Clients **SHOULD**: 126 | - Debounce rapid completion requests 127 | - Cache completion results where appropriate 128 | - Handle missing or partial results gracefully 129 | 130 | ## Security 131 | 132 | Implementations **MUST**: 133 | 134 | - Validate all completion inputs 135 | - Implement appropriate rate limiting 136 | - Control access to sensitive suggestions 137 | - Prevent completion-based information disclosure 138 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/server/utilities/logging.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Logging 3 | --- 4 | 5 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 6 | 7 | The Model Context Protocol (MCP) provides a standardized way for servers to send 8 | structured log messages to clients. Clients can control logging verbosity by setting 9 | minimum log levels, with servers sending notifications containing severity levels, 10 | optional logger names, and arbitrary JSON-serializable data. 11 | 12 | ## User Interaction Model 13 | 14 | Implementations are free to expose logging through any interface pattern that suits their 15 | needs&mdash;the protocol itself does not mandate any specific user interaction model. 16 | 17 | ## Capabilities 18 | 19 | Servers that emit log message notifications **MUST** declare the `logging` capability: 20 | 21 | ```json 22 | { 23 | "capabilities": { 24 | "logging": {} 25 | } 26 | } 27 | ``` 28 | 29 | ## Log Levels 30 | 31 | The protocol follows the standard syslog severity levels specified in 32 | [RFC 5424](https://datatracker.ietf.org/doc/html/rfc5424#section-6.2.1): 33 | 34 | | Level | Description | Example Use Case | 35 | | --------- | -------------------------------- | -------------------------- | 36 | | debug | Detailed debugging information | Function entry/exit points | 37 | | info | General informational messages | Operation progress updates | 38 | | notice | Normal but significant events | Configuration changes | 39 | | warning | Warning conditions | Deprecated feature usage | 40 | | error | Error conditions | Operation failures | 41 | | critical | Critical conditions | System component failures | 42 | | alert | Action must be taken immediately | Data corruption detected | 43 | | emergency | System is unusable | Complete system failure | 44 | 45 | ## Protocol Messages 46 | 47 | ### Setting Log Level 48 | 49 | To configure the minimum log level, clients **MAY** send a `logging/setLevel` request: 50 | 51 | **Request:** 52 | 53 | ```json 54 | { 55 | "jsonrpc": "2.0", 56 | "id": 1, 57 | "method": "logging/setLevel", 58 | "params": { 59 | "level": "info" 60 | } 61 | } 62 | ``` 63 | 64 | ### Log Message Notifications 65 | 66 | Servers send log messages using `notifications/message` notifications: 67 | 68 | ```json 69 | { 70 | "jsonrpc": "2.0", 71 | "method": "notifications/message", 72 | "params": { 73 | "level": "error", 74 | "logger": "database", 75 | "data": { 76 | "error": "Connection failed", 77 | "details": { 78 | "host": "localhost", 79 | "port": 5432 80 | } 81 | } 82 | } 83 | } 84 | ``` 85 | 86 | ## Message Flow 87 | 88 | ```mermaid 89 | sequenceDiagram 90 | participant Client 91 | participant Server 92 | 93 | Note over Client,Server: Configure Logging 94 | Client->>Server: logging/setLevel (info) 95 | Server-->>Client: Empty Result 96 | 97 | Note over Client,Server: Server Activity 98 | Server--)Client: notifications/message (info) 99 | Server--)Client: notifications/message (warning) 100 | Server--)Client: notifications/message (error) 101 | 102 | Note over Client,Server: Level Change 103 | Client->>Server: logging/setLevel (error) 104 | Server-->>Client: Empty Result 105 | Note over Server: Only sends error level<br/>and above 106 | ``` 107 | 108 | ## Error Handling 109 | 110 | Servers **SHOULD** return standard JSON-RPC errors for common failure cases: 111 | 112 | - Invalid log level: `-32602` (Invalid params) 113 | - Configuration errors: `-32603` (Internal error) 114 | 115 | ## Implementation Considerations 116 | 117 | 1. Servers **SHOULD**: 118 | 119 | - Rate limit log messages 120 | - Include relevant context in data field 121 | - Use consistent logger names 122 | - Remove sensitive information 123 | 124 | 2. Clients **MAY**: 125 | - Present log messages in the UI 126 | - Implement log filtering/search 127 | - Display severity visually 128 | - Persist log messages 129 | 130 | ## Security 131 | 132 | 1. Log messages **MUST NOT** contain: 133 | 134 | - Credentials or secrets 135 | - Personal identifying information 136 | - Internal system details that could aid attacks 137 | 138 | 2. Implementations **SHOULD**: 139 | - Rate limit messages 140 | - Validate all data fields 141 | - Control log access 142 | - Monitor for sensitive content 143 | -------------------------------------------------------------------------------- /docs/specification/2024-11-05/server/utilities/pagination.md: -------------------------------------------------------------------------------- 1 | --- 2 | title: Pagination 3 | --- 4 | 5 | {{< callout type="info" >}} **Protocol Revision**: 2024-11-05 {{< /callout >}} 6 | 7 | The Model Context Protocol (MCP) supports paginating list operations that may return 8 | large result sets. Pagination allows servers to yield results in smaller chunks rather 9 | than all at once. 10 | 11 | Pagination is especially important when connecting to external services over the 12 | internet, but also useful for local integrations to avoid performance issues with large 13 | data sets. 14 | 15 | ## Pagination Model 16 | 17 | Pagination in MCP uses an opaque cursor-based approach, instead of numbered pages. 18 | 19 | - The **cursor** is an opaque string token, representing a position in the result set 20 | - **Page size** is determined by the server, and **MAY NOT** be fixed 21 | 22 | ## Response Format 23 | 24 | Pagination starts when the server sends a **response** that includes: 25 | 26 | - The current page of results 27 | - An optional `nextCursor` field if more results exist 28 | 29 | ```json 30 | { 31 | "jsonrpc": "2.0", 32 | "id": "123", 33 | "result": { 34 | "resources": [...], 35 | "nextCursor": "eyJwYWdlIjogM30=" 36 | } 37 | } 38 | ``` 39 | 40 | ## Request Format 41 | 42 | After receiving a cursor, the client can _continue_ paginating by issuing a request 43 | including that cursor: 44 | 45 | ```json 46 | { 47 | "jsonrpc": "2.0", 48 | "method": "resources/list", 49 | "params": { 50 | "cursor": "eyJwYWdlIjogMn0=" 51 | } 52 | } 53 | ``` 54 | 55 | ## Pagination Flow 56 | 57 | ```mermaid 58 | sequenceDiagram 59 | participant Client 60 | participant Server 61 | 62 | Client->>Server: List Request (no cursor) 63 | loop Pagination Loop 64 | Server-->>Client: Page of results + nextCursor 65 | Client->>Server: List Request (with cursor) 66 | end 67 | ``` 68 | 69 | ## Operations Supporting Pagination 70 | 71 | The following MCP operations support pagination: 72 | 73 | - `resources/list` - List available resources 74 | - `resources/templates/list` - List resource templates 75 | - `prompts/list` - List available prompts 76 | - `tools/list` - List available tools 77 | 78 | ## Implementation Guidelines 79 | 80 | 1. Servers **SHOULD**: 81 | 82 | - Provide stable cursors 83 | - Handle invalid cursors gracefully 84 | 85 | 2. Clients **SHOULD**: 86 | 87 | - Treat a missing `nextCursor` as the end of results 88 | - Support both paginated and non-paginated flows 89 | 90 | 3. Clients **MUST** treat cursors as opaque tokens: 91 | - Don't make assumptions about cursor format 92 | - Don't attempt to parse or modify cursors 93 | - Don't persist cursors across sessions 94 | 95 | ## Error Handling 96 | 97 | Invalid cursors **SHOULD** result in an error with code -32602 (Invalid params). 98 | --------------------------------------------------------------------------------