# RMCP
[](https://crates.io/crates/rmcp)
[](https://docs.rs/rmcp/latest/rmcp)
An official rust Model Context Protocol SDK implementation with tokio async runtime.
## Usage
### Import
```toml
rmcp = { version = "0.1", features = ["server"] }
## or dev channel
rmcp = { git = "https://github.com/modelcontextprotocol/rust-sdk", branch = "main" }
```
### Quick start
Start a client in one line:
```rust
use rmcp::{ServiceExt, transport::TokioChildProcess};
use tokio::process::Command;
let client = ().serve(
TokioChildProcess::new(Command::new("npx").arg("-y").arg("@modelcontextprotocol/server-everything"))?
).await?;
```
#### 1. Build a transport
```rust, ignore
use tokio::io::{stdin, stdout};
let transport = (stdin(), stdout());
```
The transport type must implemented [`IntoTransport`](crate::transport::IntoTransport) trait, which allow split into a sink and a stream.
For client, the sink item is [`ClientJsonRpcMessage`](crate::model::ClientJsonRpcMessage) and stream item is [`ServerJsonRpcMessage`](crate::model::ServerJsonRpcMessage)
For server, the sink item is [`ServerJsonRpcMessage`](crate::model::ServerJsonRpcMessage) and stream item is [`ClientJsonRpcMessage`](crate::model::ClientJsonRpcMessage)
##### These types is automatically implemented [`IntoTransport`](crate::transport::IntoTransport) trait
1. The types that already implement both [`Sink`](futures::Sink) and [`Stream`](futures::Stream) trait.
2. A tuple of sink `Tx` and stream `Rx`: `(Tx, Rx)`.
3. The type that implement both [`tokio::io::AsyncRead`] and [`tokio::io::AsyncWrite`] trait.
4. A tuple of [`tokio::io::AsyncRead`] `R `and [`tokio::io::AsyncWrite`] `W`: `(R, W)`.
For example, you can see how we build a transport through TCP stream or http upgrade so easily. [examples](examples/README.md)
#### 2. Build a service
You can easily build a service by using [`ServerHandler`](crates/rmcp/src/handler/server.rs) or [`ClientHandler`](crates/rmcp/src/handler/client.rs).
```rust, ignore
let service = common::counter::Counter::new();
```
#### 3. Serve them together
```rust, ignore
// this call will finish the initialization process
let server = service.serve(transport).await?;
```
#### 4. Interact with the server
Once the server is initialized, you can send requests or notifications:
```rust, ignore
// request
let roots = server.list_roots().await?;
// or send notification
server.notify_cancelled(...).await?;
```
#### 5. Waiting for service shutdown
```rust, ignore
let quit_reason = server.waiting().await?;
// or cancel it
let quit_reason = server.cancel().await?;
```
### Use marcos to declaring tool
Use `toolbox` and `tool` macros to create tool quickly.
Check this [file](examples/servers/src/common/calculator.rs).
```rust, ignore
use rmcp::{ServerHandler, model::ServerInfo, schemars, tool};
use super::counter::Counter;
#[derive(Debug, serde::Deserialize, schemars::JsonSchema)]
pub struct SumRequest {
#[schemars(description = "the left hand side number")]
pub a: i32,
#[schemars(description = "the right hand side number")]
pub b: i32,
}
#[derive(Debug, Clone)]
pub struct Calculator;
// create a static toolbox to store the tool attributes
#[tool(tool_box)]
impl Calculator {
// async function
#[tool(description = "Calculate the sum of two numbers")]
async fn sum(&self, #[tool(aggr)] SumRequest { a, b }: SumRequest) -> String {
(a + b).to_string()
}
// sync function
#[tool(description = "Calculate the sum of two numbers")]
fn sub(
&self,
#[tool(param)]
// this macro will transfer the schemars and serde's attributes
#[schemars(description = "the left hand side number")]
a: i32,
#[tool(param)]
#[schemars(description = "the right hand side number")]
b: i32,
) -> String {
(a - b).to_string()
}
}
// impl call_tool and list_tool by querying static toolbox
#[tool(tool_box)]
impl ServerHandler for Calculator {
fn get_info(&self) -> ServerInfo {
ServerInfo {
instructions: Some("A simple calculator".into()),
..Default::default()
}
}
}
```
The only thing you should do is to make the function's return type implement `IntoCallToolResult`.
And you can just implement `IntoContents`, and the return value will be marked as success automatically.
If you return a type of `Result` where `T` and `E` both implemented `IntoContents`, it's also OK.
### Manage Multi Services
For many cases you need to manage several service in a collection, you can call `into_dyn` to convert services into the same type.
```rust, ignore
let service = service.into_dyn();
```
### Examples
See [examples](examples/README.md)
### Features
- `client`: use client side sdk
- `server`: use server side sdk
- `macros`: macros default
#### Transports
- `transport-io`: Server stdio transport
- `transport-sse-server`: Server SSE transport
- `transport-child-process`: Client stdio transport
- `transport-sse`: Client sse transport
## Related Resources
- [MCP Specification](https://spec.modelcontextprotocol.io/specification/2024-11-05/)
- [Schema](https://github.com/modelcontextprotocol/specification/blob/main/schema/2024-11-05/schema.ts)