Supply the Prompt arguments the example requires

A Prompt example supplies every required argument and no undeclared argument. Check names against the containing Prompt, including when the example comes from a reusable component. Omitted optional arguments do not need placeholder values.

Requirement

A Prompt example supplies every required Prompt argument and no undeclared argument.

Details

Rule ID: mcpdesc.prompt.example.arguments
Owner: mcpdesc
Surface: Prompt example · Path: arguments
Kind: mcpdesc-semantic
Requirement level: must
Protocol versions: independent of the MCP protocol version
Status: internal · Enforcement: internal

Required by

• MCP Description 0.9.0, Section 11.3
  • 11. Prompts: req-prompt-example-arguments

Based on

• Tier 1 — MCP schema.ts and normative specification text: MCP 2024-11-05 to 2026-07-28 schema.ts, interface PromptArgument, required (“Whether this argument must be provided”)
  • validation/mcp-schemas/2024-11-05/schema.ts#L588-L591
  • validation/mcp-schemas/2025-03-26/schema.ts#L626-L629
  • validation/mcp-schemas/2025-06-18/schema.ts#L727-L730
  • validation/mcp-schemas/2025-11-25/schema.ts#L1011-L1014
  • validation/mcp-schemas/2026-07-28/schema.ts#L1683-L1686

Examples

Valid example

Source: expected-valid/named-prompt-examples.json · Selected: /prompts/2

{
  "name": "city_briefing",
  "protocolVersions": [
    "2026-07-28"
  ],
  "arguments": [
    {
      "name": "city",
      "required": true
    },
    {
      "name": "audience"
    }
  ],
  "examples": {
    "paris-engineering": {
      "arguments": {
        "city": "Paris",
        "audience": "engineering"
      },
      "result": {
        "resultType": "complete",
        "description": "Engineering briefing for Paris",
        "messages": [
          {
            "role": "user",
            "content": {
              "type": "text",
              "text": "Summarize current engineering considerations for Paris."
            }
          },
          {
            "role": "assistant",
            "content": {
              "type": "resource_link",
              "uri": "briefing://paris/engineering",
              "name": "Paris engineering briefing",
              "mimeType": "text/markdown"
            }
          }
        ]
      }
    }
  }
}

Invalid example

Source: expected-invalid/invalid-prompt-example-semantics.json · Selected: /prompts/0/examples/unknown-and-missing/arguments

{
  "audience": "engineering",
  "rogue": "oops"
}

Invalid example

Source: expected-invalid/component-contextual-examples.json · Selected: /components/promptExamples/bad-arguments

{
  "arguments": {
    "rogue": "oops"
  },
  "result": {
    "resultType": "complete",
    "messages": [
      {
        "role": "user",
        "content": {
          "type": "text",
          "text": "Hello."
        }
      }
    ]
  }
}

Rule Source Code

prompt.yaml at immutable tag v0.9.0-rc.3.