1. Introduction

1.1 Purpose

The MCP Description Specification defines a standard format for describing the capabilities of a Model Context Protocol (MCP) server as a static, curated document.

The MCP ecosystem currently relies on runtime discovery through protocol initialization and capability inspection. While effective for dynamic interactions, this approach limits offline tooling, cross-platform interoperability, and contract-driven development workflows.

This specification addresses these limitations by providing a portable contract format for MCP servers — analogous to the role OpenAPI plays for HTTP APIs.

1.2 Goals

An MCP Description document enables:

Standardized server descriptions — a consistent structure for declaring server metadata, transports, tools, resources, prompts, and capabilities.
Offline discoverability — platforms can index and display server capabilities without establishing a runtime connection.
Tooling interoperability — documentation generators, testing frameworks, agent discovery tools, IDE integrations, and governance platforms can operate on a common format.
Contract-driven development — teams can define and validate MCP server capabilities before deployment.

1.3 Audience

This specification is intended for:

MCP server developers who publish capability descriptions
MCP client and agent developers who consume server descriptions
Platform developers building registries, documentation portals, and governance tools
Tool authors creating validators, generators, and IDE integrations

1.4 Relationship to the MCP Protocol

The MCP Description Specification does not replace the MCP protocol. It complements the protocol by providing a static description format for server capabilities.

MCP Protocol	MCP Description
Runtime communication	Static declaration
Initialize handshake	Server metadata
Tool invocation	Tool definitions
Resource fetching	Resource definitions

The MCP protocol defines runtime behavior. An MCP Description defines the server contract.

1.5 Scope

This specification defines:

The structure and semantics of an MCP Description document
JSON Schema validation rules for MCP Description documents
The specification extension mechanism for vendor-specific metadata

This specification does NOT define:

The MCP protocol itself
Runtime behavior of MCP servers or clients
The content or structure of vendor extensions (these are defined independently by extension authors)