Rust MCP Server (Modular Template)

This repository is a complete, layered MCP server scaffold in Rust using stdio transport.

Architecture

• src/domain: core types and contracts
• src/application: request handling and MCP method routing
• src/tools: tool implementations and registry
• src/infrastructure: transport implementation (stdio)
• src/main.rs: process bootstrap and runtime loop

Configuration Layer

Configuration is loaded in this order:

1. Defaults from ServerConfig
2. Optional JSON file: mcp-server.json (or path from MCP_SERVER_CONFIG_PATH)
3. Environment variable overrides

Supported environment variables:

• MCP_SERVER_NAME
• MCP_SERVER_VERSION
• MCP_SERVER_PROTOCOL_VERSION
• MCP_SERVER_TOOLS_LIST_CHANGED

An example config file is available at mcp-server.example.json.

Included Tools

• echo: returns the input message
• now: returns the current UTC timestamp in RFC3339 format

Run

Server only:

cargo run

Windows shortcut:

.\bin\run-server.bat

Client (spawns server internally):

cargo run --bin client

See CLIENT.md for more details on the client module.

VS Code task:

• Run task Run MCP Server from the Command Palette.

Test Tools (Windows)

Run unit tests:

cargo test

Run integration tests only:

cargo test --test integration_tests

Run smoke test (interactive server validation):

.\bin\test-tools.bat

See TESTS.md for full test documentation.

The server communicates over stdio using JSON-RPC framing (Content-Length headers), compatible with MCP clients.

Extend

1. Add a new tool under src/tools implementing the Tool trait.
2. Register it in ToolRegistry::new() in src/tools/mod.rs.
3. Keep protocol handling in src/application/mcp_service.rs focused on MCP method dispatch.