A synchronous Rust client for the Model Context Protocol (MCP).
sovran-mcp provides a clean, synchronous interface for interacting with MCP servers. It handles:
- Tool execution and discovery
- Prompt management
- Resource handling and subscriptions
- Server capability detection
Add to your Cargo.toml:
[dependencies]
sovran-mcp = "0.3.1"Basic example:
use sovran_mcp::{McpClient, transport::StdioTransport};
fn main() -> Result<(), sovran_mcp::McpError> {
// Create and start client
let transport = StdioTransport::new("npx", &["-y", "@modelcontextprotocol/server-everything"])?;
let mut client = McpClient::new(transport, None, None);
client.start()?;
// List available tools
if client.supports_tools() {
let tools = client.list_tools()?;
println!("Available tools: {:?}", tools);
// Call a tool
let response = client.call_tool(
"echo".to_string(),
Some(serde_json::json!({
"message": "Hello, MCP!"
}))
)?;
}
// Clean up
client.stop()?;
Ok(())
}- List available tools
- Execute tools with arguments
- Handle tool responses (text, images, resources)
- List available prompts
- Retrieve prompts with arguments
- Handle multi-part prompt messages
- List available resources
- Read resource contents
- Subscribe to resource changes
- Handle resource update notifications
- Protocol version detection
- Feature availability checking
- Experimental feature support
Support for server-initiated LLM completions:
use sovran_mcp::types::*;
struct MySamplingHandler;
impl SamplingHandler for MySamplingHandler {
fn handle_message(&self, request: CreateMessageRequest) -> Result<CreateMessageResponse, McpError> {
// Process completion request
Ok(CreateMessageResponse {
content: MessageContent::Text(TextContent {
text: "Response".to_string()
}),
model: "test-model".to_string(),
role: Role::Assistant,
stop_reason: Some("complete".to_string()),
meta: None,
})
}
}Support for resource update notifications:
use sovran_mcp::types::*;
use url::Url;
struct MyNotificationHandler;
impl NotificationHandler for MyNotificationHandler {
fn handle_resource_update(&self, uri: &Url) -> Result<(), McpError> {
println!("Resource updated: {}", uri);
Ok(())
}
}The crate uses McpError for comprehensive error handling, covering:
- Transport errors (I/O, connection issues)
- Protocol errors (JSON-RPC, serialization)
- Capability errors (unsupported features)
- Request timeouts
- Command failures
MIT License
Contributions welcome! Please feel free to submit a Pull Request.