Struct ServerBuilder 

pub struct ServerBuilder { /* private fields */ }

Fluent builder for Server

Implementations

impl ServerBuilder

pub fn new(name: impl Into<String>, version: impl Into<String>) -> Self

Create new server builder

pub fn with_capabilities(self, capabilities: ServerCapabilities) -> Self

Set server capabilities

pub fn with_instructions(self, instructions: impl Into<String>) -> Self

Set server instructions for LLMs

Instructions help LLMs understand how to use the server’s tools, resources, and prompts. They are sent during initialization and can be thought of as hints added to the system prompt.

Example

use mcp_host::prelude::*;

let server = server("my-server", "1.0.0")
    .with_instructions("Use the data tools for queries. Verify IDs before updates.")
    .build();

pub fn with_tools(self, list_changed: bool) -> Self

Enable tools capability

pub fn with_resources(self, list_changed: bool, subscribe: bool) -> Self

Enable resources capability

pub fn with_resource_templates(self) -> Self

Enable resource templates capability

pub fn with_prompts(self, list_changed: bool) -> Self

Enable prompts capability

pub fn with_logging(self) -> Self

Enable logging capability

pub fn with_tasks(self, list: bool, cancel: bool) -> Self

Enable tasks capability

pub fn add_middleware(self, middleware: MiddlewareFn) -> Self

Add middleware to the server

pub fn with_logging_middleware(self) -> Self

Add logging middleware

pub fn with_validation_middleware(self) -> Self

Add validation middleware

pub fn with_circuit_breaker(self, config: ToolBreakerConfig) -> Self

Configure circuit breakers for tools

Circuit breakers protect against cascading failures by temporarily disabling tools that are failing repeatedly.

Example

use mcp_host::prelude::*;

let server = server("my-server", "1.0.0")
    .with_circuit_breaker(ToolBreakerConfig {
        failure_threshold: 3,
        failure_window_secs: 30.0,
        half_open_timeout_secs: 15.0,
        success_threshold: 1,
    })
    .build();

pub fn with_retry(self, config: ResourceRetryConfig) -> Self

Configure retry behavior for resources

Resources will retry failed reads using exponential backoff with jitter.

Example

use mcp_host::prelude::*;

let server = server("my-server", "1.0.0")
    .with_retry(ResourceRetryConfig {
        max_attempts: 5,
        base_delay_ms: 200,
        multiplier: 2.0,
        max_delay_ms: 5000,
        jitter_factor: 1.0,
    })
    .build();

pub fn with_rate_limit( self, requests_per_second: f64, burst_capacity: usize, ) -> Self

Add rate limiting middleware

Rate limits requests using the GCRA (Generic Cell Rate Algorithm).

Arguments

• requests_per_second - Maximum requests allowed per second
• burst_capacity - Number of requests that can burst instantly

Example

use mcp_host::prelude::*;

let server = server("my-server", "1.0.0")
    .with_rate_limit(100.0, 20)  // 100 req/s with burst of 20
    .build();

pub fn with_rate_limiter(self, limiter: Arc<RateLimiter>) -> Self

Add rate limiting with custom configuration

pub fn build(self) -> Server

Build the server