What MCP enables
MCP connects AI applications with tools, data and context. A merchant can expose product search, stock queries or order functions to an assistant. The assistant discovers the tools, calls them with structured inputs and processes the results.
Connections with other protocols
- UCP can expose purchasing functions through MCP. MCP carries the tool call while UCP describes the purchase data and steps.
- MCP Apps adds interactive interfaces to tools inside an assistant. A2A connects agent applications working together on a task.
Versions and licence
- Published version
- 2026-07-28 ·
- Working draft
- —
This revision introduces a stateless core and revised authorisation, among other changes. Check SDK major versions separately from protocol revisions.
- Licence / terms
- Transition from MIT to Apache-2.0: new code and specification contributions use Apache-2.0; older contributions not yet relicensed remain MIT. Documentation outside the specification: CC-BY-4.0. SDKs have their own licence files.
Licence and terms ↗
An example flow
- A merchant exposes a stock query tool on an MCP server.
- The AI application connects its MCP client to the server and discovers the available tools.
- The assistant queries stock for a specific item using its identifier.
- The server reads stock from the merchant's system and returns a structured result.
SDKs and examples
These libraries and examples help you get started. Each entry lists the language, package and supported version.
MCP TypeScript v2
Includes: Client and server SDK
Package / module: @modelcontextprotocol/server; @modelcontextprotocol/client
Version & compatibility: Client and server each 2.3.1; Node.js ≥20
Client and server use separate packages in v2. The v1 @modelcontextprotocol/sdk line does not support revision 2026-07-28.
MCP Python
Includes: Python SDK
Package / module: mcp
Version & compatibility: 2.3.0 · Published 2 October 2026
Python ≥3.10 according to PyPI metadata.
MCP PHP
Includes: PHP SDK
Package / module: mcp/sdk
Version & compatibility: 0.9.0 · Published 18 October 2026
Experimental package line ahead of its first major release.
MCP Rust
Includes: Rust SDK
Package / module: rmcp
Version & compatibility: 3.7.0 · Published 22 October 2026
The integration can select the protocol revision and lifecycle mode.
MCP Go
Includes: Go SDK
Package / module: github.com/modelcontextprotocol/go-sdk/mcp
Version & compatibility: SDK v1.7.0+ supports revision 2026-07-28 according to its repository
The repository's compatibility matrix maps releases to protocol revisions.
MCP .NET
Includes: SDK
Package / module: ModelContextProtocol
Version & compatibility: 2.3.0 · Published 20 October 2026
Depending on the application, .Core and .AspNetCore complement the base package.
MCP Java
Includes: SDK
Package / module: io.modelcontextprotocol.sdk:mcp
Version & compatibility: Stable: 2.1.0; prerelease: 2.2.0-M1
2.2.0-M1 includes the stateless server for revision 2026-07-28; the modern client, Tasks and SEP-2243 headers are still pending in this release.
Practical integration
- Revision 2026-07-28 uses a stateless core and revised authorisation. The SDK entries describe their respective support.
- In TypeScript SDK v2, client and server have separate packages. The earlier @modelcontextprotocol/sdk v1 line remains in maintenance mode.