---
title: "Appendix A: Icon Object"
description: "MCP Description specification v0.9.0-rc.3 — Appendix A: Icon Object."
source: "https://mcpdesc.org/docs/specification/0.9.0-rc.3/appendices/"
---

---

## Appendix A: Icon Object

[<req-icon-fields>](/docs/rules/0.9.0-rc.3/mcp/icon-members#required-by "This requirement is part of rule: mcp.icon.members") The Icon object is used throughout the specification for UI display.

| Property | Type          | Required | Description                                                          |
| -------- | ------------- | -------- | -------------------------------------------------------------------- |
| src      | string (URI)  | **Yes**  | URI pointing to an icon resource (HTTP/HTTPS URL or data: URI).      |
| mimeType | string        | No       | MIME type override (e.g., "image/png", "image/svg+xml").             |
| sizes    | array<string> | No       | Sizes at which the icon can be used (e.g., "48x48", "96x96", "any"). |
| theme    | string        | No       | Theme this icon is designed for: "light" or "dark".                  |

Clients MUST support `image/png` and `image/jpeg`. Clients SHOULD also support `image/svg+xml` and `image/webp`.

---

## Appendix B: Complete Example

See [examples/full-featured.yaml](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/spec/draft/examples/full-featured.yaml) for a complete MCP Description document demonstrating a broad set of features from this specification.

---

## Appendix C: JSON Schema

The normative JSON Schema for this specification version is available at:

* [../../../schemas/mcp-description/0.9.0.json](https://github.com/mcpdesc/mcpdesc-specification/blob/v0.9.0-rc.3/schemas/mcp-description/0.9.0.json)
* `https://mcpdesc.org/schema/mcp-description/0.9.0-rc.3.json` for the current community working draft canonical schema resource
* `https://mcpdesc.org/schema/mcp-description/0.9.0.json` for the stable 0.9.0 canonical schema resource after release

Archival retrieval locations may also exist for frozen historical bytes, including the legacy Draft 3 short URI `https://mcpdesc.org/schema/0.8.0.json` and the stable 0.7.0 mirror `https://mcpdesc.org/schema/mcp-description/0.7.0.json`. Those retrieval URLs do not change the historical embedded `$id` values of the frozen schemas they mirror.

---

## Appendix D: References

### Normative References

* **\[RFC 2119\]** Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels”, RFC 2119, March 1997.
* **\[RFC 3986\]** Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax”, RFC 3986, January 2005.
* **\[RFC 6570\]** Gregorio, J., Fielding, R., Hadley, M., Nottingham, M., and D. Orchard, “URI Template”, RFC 6570, March 2012.
* **\[RFC 8259\]** Bray, T., “The JavaScript Object Notation (JSON) Data Interchange Format”, RFC 8259, December 2017.
* **\[RFC 9512\]** Bormann, C., et al., “YAML Media Type”, RFC 9512, February 2024.
* **\[YAML 1.2.2\]** Ben-Kiki, O., Evans, C., and I. döt Net, “YAML Ain’t Markup Language, Version 1.2.2”, October 2021.
* **\[JSON Schema\]** Wright, A., Andrews, H., Hutton, B., “JSON Schema: A Media Type for Describing JSON Documents”, draft-bhutton-json-schema-01, June 2022.

### Informative References

* **\[MCP Protocol\]** Anthropic, “Model Context Protocol Specification”, <https://modelcontextprotocol.io>
* **\[OpenAPI 3.1\]** OpenAPI Initiative, “OpenAPI Specification v3.1.0”, <https://spec.openapis.org/oas/v3.1.0>
* **\[Semantic Versioning\]** Preston-Werner, T., “Semantic Versioning 2.0.0”, <https://semver.org>