Struct McpClient 

pub struct McpClient { /* private fields */ }

MCP client with a background message loop.

Unlike previous versions, this type is not generic over the transport. The transport is consumed during connect() and moved into a background Tokio task that handles message multiplexing.

All public methods take &self, enabling concurrent use from multiple tasks.

Construction

use tower_mcp::client::{McpClient, StdioClientTransport};

// Simple: no handler for server-initiated requests
let transport = StdioClientTransport::spawn("server", &[]).await?;
let client = McpClient::connect(transport).await?;

// With configuration
use tower_mcp::protocol::Root;
let transport = StdioClientTransport::spawn("server", &[]).await?;
let client = McpClient::builder()
    .with_roots(vec![Root::new("file:///project")])
    .connect_simple(transport)
    .await?;

Implementations

impl McpClient

pub async fn connect<T: ClientTransport>(transport: T) -> Result<Self>

Connect with default settings and no handler.

Shorthand for McpClient::builder().connect_simple(transport).

pub async fn connect_with_handler<T, H>( transport: T, handler: H, ) -> Result<Self>

where T: ClientTransport, H: ClientHandler,

Connect with a handler for server-initiated requests.

pub fn builder() -> McpClientBuilder

Create a builder for advanced configuration.

pub fn is_initialized(&self) -> bool

Check if the client has been initialized.

pub fn is_connected(&self) -> bool

Check if the transport is still connected.

pub fn server_info(&self) -> Option<&InitializeResult>

Get the server info (available after initialization).

pub async fn initialize( &self, client_name: &str, client_version: &str, ) -> Result<&InitializeResult>

Initialize the MCP connection.

Sends the initialize request and notifications/initialized notification. Must be called before any other operations.

pub async fn list_tools(&self) -> Result<ListToolsResult>

List available tools.

pub async fn call_tool( &self, name: &str, arguments: Value, ) -> Result<CallToolResult>

Call a tool.

pub async fn list_resources(&self) -> Result<ListResourcesResult>

List available resources.

pub async fn read_resource(&self, uri: &str) -> Result<ReadResourceResult>

Read a resource.

pub async fn list_prompts(&self) -> Result<ListPromptsResult>

List available prompts.

pub async fn list_tools_with_cursor( &self, cursor: Option<String>, ) -> Result<ListToolsResult>

List tools with an optional pagination cursor.

pub async fn list_resources_with_cursor( &self, cursor: Option<String>, ) -> Result<ListResourcesResult>

List resources with an optional pagination cursor.

pub async fn list_resource_templates( &self, ) -> Result<ListResourceTemplatesResult>

List resource templates.

pub async fn list_resource_templates_with_cursor( &self, cursor: Option<String>, ) -> Result<ListResourceTemplatesResult>

List resource templates with an optional pagination cursor.

pub async fn list_prompts_with_cursor( &self, cursor: Option<String>, ) -> Result<ListPromptsResult>

List prompts with an optional pagination cursor.

pub async fn list_all_tools(&self) -> Result<Vec<ToolDefinition>>

List all tools, following pagination cursors until exhausted.

pub async fn list_all_resources(&self) -> Result<Vec<ResourceDefinition>>

List all resources, following pagination cursors until exhausted.

pub async fn list_all_resource_templates( &self, ) -> Result<Vec<ResourceTemplateDefinition>>

List all resource templates, following pagination cursors until exhausted.

pub async fn list_all_prompts(&self) -> Result<Vec<PromptDefinition>>

List all prompts, following pagination cursors until exhausted.

pub async fn call_tool_text( &self, name: &str, arguments: Value, ) -> Result<String>

Call a tool and return the concatenated text content.

Returns the text from all Text items joined together. If the tool result indicates an error (is_error is true), returns an error with the text content as the message.

For more control over the result, use call_tool().

pub async fn get_prompt( &self, name: &str, arguments: Option<HashMap<String, String>>, ) -> Result<GetPromptResult>

Get a prompt.

pub async fn ping(&self) -> Result<()>

Ping the server.

pub async fn complete( &self, reference: CompletionReference, argument_name: &str, argument_value: &str, ) -> Result<CompleteResult>

Request completion suggestions from the server.

pub async fn complete_prompt_arg( &self, prompt_name: &str, argument_name: &str, argument_value: &str, ) -> Result<CompleteResult>

Request completion for a prompt argument.

pub async fn complete_resource_uri( &self, resource_uri: &str, argument_name: &str, argument_value: &str, ) -> Result<CompleteResult>

Request completion for a resource URI.

pub async fn request<P: Serialize, R: DeserializeOwned>( &self, method: &str, params: &P, ) -> Result<R>

Send a raw typed request to the server.

pub async fn notify<P: Serialize>(&self, method: &str, params: &P) -> Result<()>

Send a raw typed notification to the server.

pub async fn roots(&self) -> Vec<Root>

Get the current roots.

pub async fn set_roots(&self, roots: Vec<Root>) -> Result<()>

Set roots and notify the server if initialized.

pub async fn add_root(&self, root: Root) -> Result<()>

Add a root and notify the server if initialized.

pub async fn remove_root(&self, uri: &str) -> Result<bool>

Remove a root by URI and notify the server if initialized.

pub async fn list_roots(&self) -> ListRootsResult

Get the roots list result (for responding to server’s roots/list request).

pub async fn shutdown(self) -> Result<()>

Gracefully shut down the client and close the transport.

Trait Implementations

impl Drop for McpClient

fn drop(&mut self)

Executes the destructor for this type.