---
title: "Select an applicable declaration for projection"
description: "Native projection selects a Tool, Resource, Resource Template, or Prompt by its identifier in one protocol view. A declaration outside that view cannot be projected for that versio"
source: "https://mcpdesc.org/docs/rules/0.9.0-rc.3/mcpdesc/projection-declaration-applicable/"
---

Native projection selects a Tool, Resource, Resource Template, or Prompt by its identifier in one protocol view. A declaration outside that view cannot be projected for that version. Check the identifier and the declaration’s inherited or explicit scope.

## Requirement

Native projection selects one declaration of the requested kind and identifier in the Effective Protocol View for the protocol version.

## Details

**Rule ID:** `mcpdesc.projection.declaration-applicable`  
**Owner:** mcpdesc  
**Surface:** Native projection  
**Kind:** mcpdesc-semantic  
**Requirement level:** must  
**Status:** delegated · **Enforcement:** external

## 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 4.14, step 3**  
  * 4\. Versioning: [req-native-projection-declaration-applicable](https://mcpdesc.org/docs/specification/0.9.0-rc.3/versioning#req-native-projection-declaration-applicable)

## Notes

Implemented by @mcpdesc/core; this repository checks the fixtures with scripts/test-projection-fixtures.mjs.

## Examples

### Projection fails

Source: [projection-fixtures/tool-not-applicable-2024-11-05.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/projection-fixtures/tool-not-applicable-2024-11-05.json) · Selected: `/expectedError`

```json
"projection-declaration-not-applicable"
```

### Projection fails

Source: [projection-fixtures/resource-template-not-applicable-2025-03-26.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/projection-fixtures/resource-template-not-applicable-2025-03-26.json) · Selected: `/expectedError`

```json
"projection-declaration-not-applicable"
```

## Rule Source Code

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