weather-server-rust

A Simple MCP Weather Server written in Rust

A minimal MCP server that exposes US weather data from the National Weather Service API as two tools:

• get_forecast – get the forecast for a location (takes latitude and longitude)
• get_alerts – get active weather alerts for a US state (takes a two-letter state code)

This example accompanies the Build an MCP server tutorial.

Prerequisites

• Rust 1.88+ and Cargo

Build and run

cargo build --release
./target/release/weather

Or, during development:

cargo run

The server communicates over stdio, so running it directly just waits for a client on stdin. To see it in action, launch it from one of the client examples in this repository, for example:

cd ../mcp-client-rust
cargo run -- ../weather-server-rust/target/release/weather

Structured content

Both tools declare an output_schema and return structured_content. get_forecast returns an object; get_alerts returns a top-level JSON array, which protocol revision 2026-07-28 is the first to allow — see Structured Content in the spec.

Note that an array-rooted schema requires a 2026-07-28 client: rmcp sends it as written on every connection rather than projecting it down, so an older client rejects the tool list.