---
title: "Match client requirements to the protocol version"
description: "Client capabilities and their settings change across MCP protocol versions. Check each declared requirement against every version in the primitive's effective scope. Split variants"
source: "https://mcpdesc.org/docs/rules/0.9.0-rc.3/mcp/client-capabilities-protocol-shape/"
---

Client capabilities and their settings change across MCP protocol versions. Check each declared requirement against every version in the primitive’s effective scope. Split variants when a requirement cannot be represented consistently across that scope.

## Requirement

Each client capability requirement and nested member exists in every applicable protocol version’s ClientCapabilities type, with object values and a boolean listChanged.

## Details

**Rule ID:** `mcp.client-capabilities.protocol-shape`  
**Owner:** mcp  
**Surface:** ClientCapabilities · **Path:** `clientRequirements`  
**Kind:** structural  
**Requirement level:** must  
**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, Section 8.5**  
  * 8\. Capabilities: [req-client-requirements-protocol-version-valid](https://mcpdesc.org/docs/specification/0.9.0-rc.3/capabilities#req-client-requirements-protocol-version-valid)
  * 1. Capabilities: [req-client-requirements-values](https://mcpdesc.org/docs/specification/0.9.0-rc.3/capabilities#req-client-requirements-values)
  * 1. Capabilities: [req-client-requirements-extensions](https://mcpdesc.org/docs/specification/0.9.0-rc.3/capabilities#req-client-requirements-extensions)

## Based on

* **Tier 1 — MCP schema.ts and normative specification text:** MCP 2024-11-05 to 2026-07-28 schema.ts, interface ClientCapabilities (members and nested members per protocol version)  
  * [validation/mcp-schemas/2024-11-05/schema.ts#L182-L203](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/schema/2024-11-05/schema.ts#L182-L203)
  * [validation/mcp-schemas/2025-03-26/schema.ts#L202-L223](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/schema/2025-03-26/schema.ts#L202-L223)
  * [validation/mcp-schemas/2025-06-18/schema.ts#L224-L251](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/schema/2025-06-18/schema.ts#L224-L251)
  * [validation/mcp-schemas/2025-11-25/schema.ts#L305-L379](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/schema/2025-11-25/schema.ts#L305-L379)
  * [validation/mcp-schemas/2026-07-28/schema.ts#L711-L786](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/schema/2026-07-28/schema.ts#L711-L786)

## Examples

### Valid example

Source: [expected-valid/client-capability-requirements.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/fixtures/expected-valid/client-capability-requirements.json) · Selected: `/tools/0/clientRequirements`

```json
{
  "tasks": {
    "requests": {
      "sampling": {
        "createMessage": {}
      }
    }
  }
}
```

### Invalid example

Source: [expected-invalid/protocol-version-incompatible-client-capability-requirements.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/fixtures/expected-invalid/protocol-version-incompatible-client-capability-requirements.json) · Selected: `/tools/0/clientRequirements`

```json
{
  "tasks": {
    "list": {}
  }
}
```

### Invalid example

Source: [expected-invalid/invalid-client-requirement-value.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/fixtures/expected-invalid/invalid-client-requirement-value.json) · Selected: `/tools/0/clientRequirements/roots`

```json
{
  "listChanged": "yes"
}
```

## Rule Source Code

[capabilities.yaml](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/validation/rules/capabilities.yaml) at immutable tag [v0.9.0-rc.3](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft).