Check completion example protocol support

MCP Description does not support completion examples for MCP 2024-11-05, despite the underlying protocol defining completion. The registry records that deliberate historical limitation. Scope completion examples to supported versions instead of treating this as a missing capability advertisement.

Requirement

Completion examples are available in every protocol version that defines completion/complete and CompleteResult.

Details

Rule ID: mcp.completion.protocol-version
Owner: mcp
Surface: CompleteResult
Kind: structural
Requirement level: Not specified in the rule record
Status: internal · Enforcement: internal

Protocol version applicability

`2024-11-05`	`2025-03-26`	`2025-06-18`	`2025-11-25`	`2026-07-28`
applies	applies	applies	applies	applies

Required by

MCP Description 0.9.0, Sections 10.4.6 and 11.4 (no completion examples for MCP 2024-11-05)
- 10. Resources and Resource Templates: req-template-completion-protocol-versions
- 1. Prompts: req-prompt-completion-protocol-versions

Based on

Tier 1 — MCP schema.ts and normative specification text: MCP 2024-11-05 schema.ts, interfaces CompleteRequest (method completion/complete) and CompleteResult; the ServerCapabilities.completions capability is added in MCP 2025-03-26

Gaps and arbitrations

Examples

Valid example

Source: expected-warning/legacy-completion-examples.json · Selected: /resourceTemplates/0/completionExamples/issue-prefix

{
  "argument": {
    "name": "issue",
    "value": "12"
  },
  "result": {
    "completion": {
      "values": [
        "120",
        "121",
        "129"
      ],
      "hasMore": true,
      "total": 14
    },
    "_meta": {
      "trace": "c1"
    }
  }
}

Invalid example

Source: expected-invalid/invalid-completion-example-semantics.json · Selected: /prompts/0/completionExamples

{
  "unsupported-version": {
    "argument": {
      "name": "topic",
      "value": "ch"
    },
    "result": {
      "completion": {
        "values": [
          "chess"
        ]
      }
    }
  }
}

Rule Source Code

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