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Version: 1.1.0

Resources

Resources represent data that clients can read from your server. They can be static (files, documents) or dynamic (template-based).

Static Resources with mcp_resource​

#[macros::mcp_resource(
    uri = "hello.txt",
    name = "Hello Text",
    description = "A plain text greeting",
    mime_type = "text/plain",
)]
#[derive(Debug, macros::JsonSchema)]
pub struct HelloResource;

The macro generates HelloResource::resource(), resource_uri(), resource_name(), resource_mime_type(), and a RESOURCE_URI constant. Reading the content is up to you - see handle_read_resource_request below.

Resource Templates with mcp_resource_template​

#[macros::mcp_resource_template(
    uri = "users://{user_id}/profile",
    name = "User Profile",
    description = "Profile data for a specific user",
    mime_type = "application/json",
)]
#[derive(Debug, macros::JsonSchema)]
pub struct UserProfileTemplate;

Handler Methods​

async fn handle_list_resources_request(
    &self, _params: Option<PaginatedRequestParams>, _runtime: Arc<dyn McpServer>,
) -> Result<ListResourcesResult, RpcError> {
    Ok(ListResourcesResult {
        resources: vec![HelloResource::resource()],
        meta: None, next_cursor: None,
    })
}

async fn handle_list_resource_templates_request(
    &self, _params: Option<PaginatedRequestParams>, _runtime: Arc<dyn McpServer>,
) -> Result<ListResourceTemplatesResult, RpcError> {
    Ok(ListResourceTemplatesResult {
        resource_templates: vec![UserProfileTemplate::resource_template()],
        meta: None, next_cursor: None,
    })
}

async fn handle_read_resource_request(
    &self, params: ReadResourceRequestParams, _runtime: Arc<dyn McpServer>,
) -> Result<ReadResourceResult, RpcError> {
    match params.uri.as_str() {
        HelloResource::RESOURCE_URI => {
            let text = tokio::fs::read_to_string(HelloResource::RESOURCE_URI)
                .await
                .map_err(|err| RpcError::internal_error().with_message(err.to_string()))?;
            let contents = TextResourceContents::new(text, HelloResource::RESOURCE_URI)
                .with_mime_type("text/plain");
            Ok(ReadResourceResult {
                contents: vec![contents.into()],
                meta: None,
            })
        }
        _ => Err(RpcError::invalid_params().with_message("unknown resource")),
    }
}

Add the resources capability to ServerCapabilities in your InitializeResult (see Quickstart for the full setup):

capabilities: ServerCapabilities {
    resources: Some(ServerCapabilitiesResources::default()),
    ..Default::default()
},