a907aead99Align with other examples — no example ships a Dockerfile or its own .gitignore. Rust build artifacts are now covered by the repo-level .gitignore instead. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
73 lines
2.4 KiB
Markdown
73 lines
2.4 KiB
Markdown
# Calculator Rust Binary Example
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Demonstrates packaging a compiled Rust binary as an MCP Bundle using the `binary` server type. Based on the [official Rust MCP SDK calculator example](https://github.com/modelcontextprotocol/rust-sdk/tree/main/examples/servers).
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## What is Binary Server Type?
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Unlike `node` or `uv` server types where the source code is bundled and executed by a runtime, the `binary` server type packages a pre-compiled native executable. This is useful for:
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- Rust, Go, C/C++ MCP servers
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- Performance-sensitive workloads
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- Servers with no runtime dependencies
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The tradeoff is that binaries are platform-specific — you need a separate build for each target OS/architecture.
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## Structure
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```
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calculator-rust/
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├── manifest.json # server.type = "binary"
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├── Cargo.toml # Rust project
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├── .mcpbignore # Exclude source from bundle
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└── src/
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└── main.rs # Calculator MCP server (~80 LOC)
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```
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After building, the `server/` directory is created with the compiled binary.
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## Building
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Requires [Rust](https://rustup.rs/) 1.85+.
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```bash
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cd examples/calculator-rust
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cargo build --release
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mkdir -p server
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cp target/release/mcp-calculator server/
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```
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## Packing
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```bash
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mcpb pack examples/calculator-rust
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```
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The `.mcpbignore` file excludes source code and build artifacts — only `manifest.json` and `server/mcp-calculator` end up in the bundle.
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## Testing
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```bash
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# MCP protocol handshake
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echo '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}' \
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| ./server/mcp-calculator
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# Tool call
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(printf '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}\n'
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printf '{"jsonrpc":"2.0","method":"notifications/initialized"}\n'
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printf '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"sum","arguments":{"a":3,"b":4}}}\n'
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sleep 1) | ./server/mcp-calculator
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```
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Expected: `sum(3, 4)` returns `{"text":"7"}`.
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## Tools
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- **sum** — Calculate the sum of two numbers
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- **sub** — Calculate the difference of two numbers
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## Notes
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- Binary size: ~2.5 MB (stripped, LTO enabled)
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- The `Cargo.toml` uses `edition = "2024"` (Rust 1.85+)
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- Logs are written to stderr via `tracing`, so they don't interfere with MCP's stdio transport
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- Uses the [rmcp](https://crates.io/crates/rmcp) crate (official Rust MCP SDK)
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