---
title: "Use root metadata only where supported"
description: "Root entries acquire _meta from MCP 2025-06-18. This is different from metadata on the surrounding roots result. Remove misplaced metadata or scope the containing example to protoc"
source: "https://mcpdesc.org/docs/rules/0.9.0-rc.3/mcp/root-meta-protocol-version/"
---

Root entries acquire \_meta from MCP 2025-06-18\. This is different from metadata on the surrounding roots result. Remove misplaced metadata or scope the containing example to protocol versions that define it.

## Requirement

A root in a roots response may carry \_meta from MCP 2025-06-18.

## Details

**Rule ID:** `mcp.root.meta.protocol-version`  
**Owner:** mcp  
**Surface:** Root · **Path:** `_meta`  
**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, Sections 3.5, 3.6, and 9.4**  
  * 3\. Document Structure: [req-meta-protocol-version-availability](https://mcpdesc.org/docs/specification/0.9.0-rc.3/document-structure#req-meta-protocol-version-availability)
  * 1. Tools: [req-interaction-protocol-version-valid](https://mcpdesc.org/docs/specification/0.9.0-rc.3/tools#req-interaction-protocol-version-valid)

## Based on

* **Tier 1 — MCP schema.ts and normative specification text:** MCP 2024-11-05 and 2025-03-26 schema.ts, interface Root (uri, name); MCP 2025-06-18 to 2026-07-28 schema.ts, interface Root (adds \_meta)  
  * [validation/mcp-schemas/2024-11-05/schema.ts#L1041-L1059](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/schema/2024-11-05/schema.ts#L1041-L1059)
  * [validation/mcp-schemas/2025-03-26/schema.ts#L1182-L1200](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/schema/2025-03-26/schema.ts#L1182-L1200)
  * [validation/mcp-schemas/2025-06-18/schema.ts#L1415-L1440](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/schema/2025-06-18/schema.ts#L1415-L1440)
  * [validation/mcp-schemas/2025-11-25/schema.ts#L2111-L2136](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/schema/2025-11-25/schema.ts#L2111-L2136)
  * [validation/mcp-schemas/2026-07-28/schema.ts#L2746-L2775](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/dae694f61a31f7a3ec2af3aff709e11f70f61e48/schema/2026-07-28/schema.ts#L2746-L2775)

## Examples

### Valid example

Source: [expected-warning/open-step-responses-before-2026.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/fixtures/expected-warning/open-step-responses-before-2026.json) · Selected: `/tools/0/interactionExamples/approved/steps/0/response/roots/0`

```json
{
  "uri": "file:///workspace/example",
  "_meta": {
    "trace": "root1"
  }
}
```

### Invalid example

Source: [expected-invalid/root-meta-before-2025-06-18.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/fixtures/expected-invalid/root-meta-before-2025-06-18.json) · Selected: `/tools/0/interactionExamples/with-root-meta/steps/0/response/roots/0`

```json
{
  "uri": "file:///workspace/example",
  "_meta": {
    "trace": "root1"
  }
}
```

## Rule Source Code

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