Elicitation

The Model Context Protocol (MCP) provides a standardized way for servers to request additional information from users through the client during interactions. This flow allows clients to maintain control over user interactions and data sharing while enabling servers to gather necessary information dynamically. Servers can request structured data from users with optional JSON schemas to validate responses.

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User Interaction Model

Elicitation in MCP allows servers to implement interactive workflows by enabling user input requests to occur nested inside other MCP server features.

Implementations are free to expose elicitation through any interface pattern that suits their needs—the protocol itself does not mandate any specific user interaction model.

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Capabilities

Clients that support elicitation MUST declare the elicitation capability during initialization:

{
  "capabilities": {
    "elicitation": {}
  }
}

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Protocol Messages

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Creating Elicitation Requests

To request information from a user, servers send an elicitation/create request:

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Simple Text Request

Request:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "elicitation/create",
  "params": {
    "message": "Please provide your GitHub username",
    "requestedSchema": {
      "type": "object",
      "properties": {
        "name": {
          "type": "string",
        },
      },
      "required": ["name"]
    }
  }
}

Response:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "action": "accept",
    "content": {
      "name": "octocat"
    }
  }
}

​

Structured Data Request

Request:

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "elicitation/create",
  "params": {
    "message": "Please provide your contact information",
    "requestedSchema": {
      "type": "object",
      "properties": {
        "name": {
          "type": "string",
          "description": "Your full name"
        },
        "email": {
          "type": "string",
          "format": "email",
          "description": "Your email address"
        },
        "age": {
          "type": "number",
          "minimum": 18,
          "description": "Your age"
        }
      },
      "required": ["name", "email"]
    }
  }
}

Response:

{
  "jsonrpc": "2.0",
  "id": 2,
  "result": {
    "action": "accept",
    "content": {
      "name": "Monalisa Octocat",
      "email": "[email protected]",
      "age": 30
    }
  }
}

Decline Response Example:

{
  "jsonrpc": "2.0",
  "id": 2,
  "result": {
    "action": "decline"
  }
}

Cancel Response Example:

{
  "jsonrpc": "2.0",
  "id": 2,
  "result": {
    "action": "cancel"
  }
}

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Message Flow

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Request Schema

The requestedSchema field allows servers to define the structure of the expected response using a restricted subset of JSON Schema. To simplify implementation for clients, elicitation schemas are limited to flat objects with primitive properties only:

"requestedSchema": {
  "type": "object",
  "properties": {
    "propertyName": {
      "type": "string",
      "title": "Display Name",
      "description": "Description of the property"
    },
    "anotherProperty": {
      "type": "number",
      "minimum": 0,
      "maximum": 100
    }
  },
  "required": ["propertyName"]
}

​

Supported Schema Types

The schema is restricted to these primitive types:

1. String Schema

   {
     "type": "string",
     "title": "Display Name",
     "description": "Description text",
     "minLength": 3,
     "maxLength": 50,
     "pattern": "^[A-Za-z]+$",
     "format": "email"
   }

   Supported formats: email, uri, date, date-time

2. Number Schema

   {
     "type": "number", // or "integer"
     "title": "Display Name",
     "description": "Description text",
     "minimum": 0,
     "maximum": 100
   }

3. Boolean Schema

   {
     "type": "boolean",
     "title": "Display Name",
     "description": "Description text",
     "default": false
   }

4. Enum Schema

   {
     "type": "string",
     "title": "Display Name",
     "description": "Description text",
     "enum": ["option1", "option2", "option3"],
     "enumNames": ["Option 1", "Option 2", "Option 3"]
   }

Clients can use this schema to:

1. Generate appropriate input forms
2. Validate user input before sending
3. Provide better guidance to users

Note that complex nested structures, arrays of objects, and other advanced JSON Schema features are intentionally not supported to simplify client implementation.

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Response Actions

Elicitation responses use a three-action model to clearly distinguish between different user actions:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "action": "accept", // or "decline" or "cancel"
    "content": {
      "propertyName": "value",
      "anotherProperty": 42
    }
  }
}

The three response actions are:

1. Accept (action: "accept"): User explicitly approved and submitted with data

   • The content field contains the submitted data matching the requested schema
   • Example: User clicked “Submit”, “OK”, “Confirm”, etc.

2. Decline (action: "decline"): User explicitly rejected the request

   • The content field is typically omitted
   • Example: User clicked “Decline”, “Reject”, “No”, etc.

3. Cancel (action: "cancel"): User dismissed without making an explicit choice

   • The content field is typically omitted
   • Example: User closed the dialog, clicked outside, pressed Escape, etc.

Servers should handle each state appropriately:

• Accept: Process the submitted data
• Decline: Handle explicit rejection (e.g., offer alternatives)
• Cancel: Handle dismissal (e.g., prompt again later)

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Security Considerations

1. Servers MUST NOT request sensitive information through elicitation
2. Clients SHOULD implement user approval controls
3. Both parties SHOULD validate elicitation content against the provided schema
4. Clients SHOULD provide clear indication of which server is requesting information
5. Clients SHOULD allow users to reject elicitation requests at any time
6. Clients SHOULD implement rate limiting
7. Clients SHOULD present elicitation requests in a way that makes it clear what information is being requested and why