--- title: "Project a document to one MCP protocol version" description: "A single-version projection validates the source, keeps the declarations whose effective scope includes the protocol version, removes their scopes, and keeps everything else unchan" source: "https://mcpdesc.org/docs/rules/0.9.0-rc.3/mcpdesc/view-projection/" --- A single-version projection validates the source, keeps the declarations whose effective scope includes the protocol version, removes their scopes, and keeps everything else unchanged: security forms, examples, client requirements, tags, extensions, and the components still referenced. ## Requirement An Effective Protocol View is a valid document for one protocol version that keeps the applicable declarations and preserves their content, security semantics, and referenced components. ## Details **Rule ID:** `mcpdesc.view.projection` **Owner:** mcpdesc **Surface:** Effective Protocol View **Kind:** mcpdesc-semantic **Requirement level:** must **Protocol versions:** independent of the MCP protocol version **Status:** delegated · **Enforcement:** external ## Required by * **MCP Description 0.9.0, Section 4.12, and the view requirements of Sections 3 to 17** * 4\. Versioning: [req-view-projection](https://mcpdesc.org/docs/specification/0.9.0-rc.3/versioning#req-view-projection) * 1. Versioning: [req-view-projection-transports](https://mcpdesc.org/docs/specification/0.9.0-rc.3/versioning#req-view-projection-transports) * 1. Document Structure: [req-security-empties-preserved](https://mcpdesc.org/docs/specification/0.9.0-rc.3/document-structure#req-security-empties-preserved) * 1. Security: [req-security-empty-distinction](https://mcpdesc.org/docs/specification/0.9.0-rc.3/security#req-security-empty-distinction) * 1. Security: [req-security-projection](https://mcpdesc.org/docs/specification/0.9.0-rc.3/security#req-security-projection) * 1. Serialization: [req-serialization-empty-values-preserved](https://mcpdesc.org/docs/specification/0.9.0-rc.3/serialization#req-serialization-empty-values-preserved) * 1. Tools: [req-tool-example-views-preserved](https://mcpdesc.org/docs/specification/0.9.0-rc.3/tools#req-tool-example-views-preserved) * 1. Tools: [req-interaction-views-preserved](https://mcpdesc.org/docs/specification/0.9.0-rc.3/tools#req-interaction-views-preserved) * 1. Capabilities: [req-client-requirements-views](https://mcpdesc.org/docs/specification/0.9.0-rc.3/capabilities#req-client-requirements-views) * 1. Resources and Resource Templates: [req-resource-example-views](https://mcpdesc.org/docs/specification/0.9.0-rc.3/resources#req-resource-example-views) * 1. Resources and Resource Templates: [req-template-completion-views](https://mcpdesc.org/docs/specification/0.9.0-rc.3/resources#req-template-completion-views) * 1. Prompts: [req-prompt-example-views](https://mcpdesc.org/docs/specification/0.9.0-rc.3/prompts#req-prompt-example-views) * 1. Prompts: [req-prompt-completion-views](https://mcpdesc.org/docs/specification/0.9.0-rc.3/prompts#req-prompt-completion-views) * 1. Tags: [req-tags-views](https://mcpdesc.org/docs/specification/0.9.0-rc.3/tags#req-tags-views) * 1. Specification Extensions: [req-extension-views](https://mcpdesc.org/docs/specification/0.9.0-rc.3/specification-extensions#req-extension-views) * 1. Reusable Components and Local References: [req-component-pruning](https://mcpdesc.org/docs/specification/0.9.0-rc.3/components#req-component-pruning) ## Notes Checked by the cases in view-fixtures/, which scripts/test-view-fixtures.mjs recomputes with the reference operations of scripts/mcpdesc-views.mjs. Implementations such as @mcpdesc/core must pass them. ## Examples ### View succeeds Source: [view-fixtures/view-client-requirements-2026-07-28.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-client-requirements-2026-07-28.json) · Selected: `/expected` ```json "expected/view-client-requirements-2026-07-28.json" ``` ### View succeeds Source: [view-fixtures/view-completion-examples-2026-07-28.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-completion-examples-2026-07-28.json) · Selected: `/expected` ```json "expected/view-completion-examples-2026-07-28.json" ``` ### View succeeds Source: [view-fixtures/view-component-pruning-2026-07-28.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-component-pruning-2026-07-28.json) · Selected: `/expected` ```json "expected/view-component-pruning-2026-07-28.json" ``` ### View succeeds Source: [view-fixtures/view-prompt-examples-2026-07-28.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-prompt-examples-2026-07-28.json) · Selected: `/expected` ```json "expected/view-prompt-examples-2026-07-28.json" ``` ### View succeeds Source: [view-fixtures/view-protocol-scoped-primitives-2025-11-25.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-protocol-scoped-primitives-2025-11-25.json) · Selected: `/expected` ```json "expected/view-protocol-scoped-primitives-2025-11-25.json" ``` ### View succeeds Source: [view-fixtures/view-protocol-scoped-primitives-2026-07-28.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-protocol-scoped-primitives-2026-07-28.json) · Selected: `/expected` ```json "expected/view-protocol-scoped-primitives-2026-07-28.json" ``` ### View succeeds Source: [view-fixtures/view-resource-examples-2026-07-28.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-resource-examples-2026-07-28.json) · Selected: `/expected` ```json "expected/view-resource-examples-2026-07-28.json" ``` ### View succeeds Source: [view-fixtures/view-security-forms-2025-11-25.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-security-forms-2025-11-25.json) · Selected: `/expected` ```json "expected/view-security-forms-2025-11-25.json" ``` ### View succeeds Source: [view-fixtures/view-security-forms-2026-07-28.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-security-forms-2026-07-28.json) · Selected: `/expected` ```json "expected/view-security-forms-2026-07-28.json" ``` ### View succeeds Source: [view-fixtures/view-specification-extensions-2025-11-25.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-specification-extensions-2025-11-25.json) · Selected: `/expected` ```json "expected/view-specification-extensions-2025-11-25.json" ``` ### View succeeds Source: [view-fixtures/view-tool-interaction-examples-2025-11-25.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-tool-interaction-examples-2025-11-25.json) · Selected: `/expected` ```json "expected/view-tool-interaction-examples-2025-11-25.json" ``` ### View fails Source: [view-fixtures/view-protocol-version-not-declared.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-protocol-version-not-declared.json) · Selected: `/expectedFailure` ```json "req-view-projection" ``` ### View fails Source: [view-fixtures/view-source-invalid.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/view-fixtures/view-source-invalid.json) · Selected: `/expectedFailure` ```json "req-view-projection" ``` ## 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).