mcpField
C
Calculator (Rust Binary)

Calculator (Rust Binary)

VerifiedLocal
github.com/modelcontextprotocolDeveloper Tools2.2kUpdated 27w ago
Repository

About Calculator (Rust Binary)

Calculator (Rust Binary) is an example MCP server packaged as a compiled Rust executable in an MCP Bundle. It demonstrates the binary server type for Rust projects and other workloads that need a native binary.

Key features

  1. 01Rust binary MCP server
  2. 02Sum and difference tools
  3. 03MCP Bundle binary packaging example
  4. 04Stdio protocol communication

Use cases

  1. 01Package a Rust MCP server as a binary bundle
  2. 02Test calculator tool calls over MCP

MCP support

The server exposes `sum` and `sub` tools to MCP clients over stdio. It is packaged as a binary-type MCP Bundle.

#dxt#desktop-extensions#calculator#rust#binary#example

Configuration

Local server config is the same for every client. Copy it into your client’s MCP config file.

No install method listed yet

We haven’t collected a package or remote endpoint for this server. Follow the instructions in the project README.

Repository

Tools

2

Saved tool list · updated 2w ago

This tool takes no parameters.

Details

From the project README

Calculator Rust Binary Example

Demonstrates packaging a compiled Rust binary as an MCP Bundle using the binary server type. Based on the official Rust MCP SDK calculator example.

What is Binary Server Type?

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:

  • Rust, Go, C/C++ MCP servers
  • Performance-sensitive workloads
  • Servers with no runtime dependencies

The tradeoff is that binaries are platform-specific — you need a separate build for each target OS/architecture.

Structure

calculator-rust/
├── manifest.json       # server.type = "binary"
├── Cargo.toml          # Rust project
├── .mcpbignore         # Exclude source from bundle
└── src/
    └── main.rs         # Calculator MCP server (~80 LOC)

After building, the server/ directory is created with the compiled binary.

Building

Requires Rust 1.85+.

cd examples/calculator-rust
cargo build --release
mkdir -p server
cp target/release/mcp-calculator server/

Packing

mcpb pack examples/calculator-rust

The .mcpbignore file excludes source code and build artifacts — only manifest.json and server/mcp-calculator end up in the bundle.

Testing

# MCP protocol handshake
echo '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}' \
  | ./server/mcp-calculator

# Tool call
(printf '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"1.0"}}}\n'
printf '{"jsonrpc":"2.0","method":"notifications/initialized"}\n'
printf '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"sum","arguments":{"a":3,"b":4}}}\n'
sleep 1) | ./server/mcp-calculator

Expected: sum(3, 4) returns {"text":"7"}.

Tools

  • sum — Calculate the sum of two numbers
  • sub — Calculate the difference of two numbers

Notes

  • Binary size: ~2.5 MB (stripped, LTO enabled)
  • The Cargo.toml uses edition = "2024" (Rust 1.85+)
  • Logs are written to stderr via tracing, so they don't interfere with MCP's stdio transport
  • Uses the rmcp crate (official Rust MCP SDK)

Comments

Markdown supported

New to MCP?

From what the protocol is to installing your first server, these answers cover most first questions.

An open protocol that defines how AI applications connect to external tools and data in a uniform way. Clients talk to the model; MCP servers provide tools, resources and prompt templates. They exchange standard messages, so one server can be reused by many clients.