fix: gate optional dependencies behind feature flags (#672)

crates/rmcp/src/lib.rs

@@ -24,7 +24,9 @@ pub use service::{RoleClient, serve_client};
 pub use service::{RoleServer, serve_server};
 
 pub mod handler;
+#[cfg(feature = "server")]
 pub mod task_manager;
+#[cfg(any(feature = "client", feature = "server"))]
 pub mod transport;
 
 // re-export
@@ -32,7 +34,7 @@ pub mod transport;
 pub use pastey::paste;
 #[cfg(all(feature = "macros", feature = "server"))]
 pub use rmcp_macros::*;
-#[cfg(any(feature = "macros", feature = "server"))]
+#[cfg(any(feature = "server", feature = "schemars"))]
 pub use schemars;
 #[cfg(feature = "macros")]
 pub use serde;

crates/rmcp/src/model/capabilities.rs

@@ -1,5 +1,8 @@
-use std::{collections::BTreeMap, marker::PhantomData};
+use std::collections::BTreeMap;
+#[cfg(any(feature = "server", feature = "macros"))]
+use std::marker::PhantomData;
 
+#[cfg(any(feature = "server", feature = "macros"))]
 use pastey::paste;
 use serde::{Deserialize, Serialize};
 
@@ -300,6 +303,7 @@ pub struct ServerCapabilities {
     pub tasks: Option<TasksCapability>,
 }
 
+#[cfg(any(feature = "server", feature = "macros"))]
 macro_rules! builder {
     ($Target: ident {$($f: ident: $T: ty),* $(,)?}) => {
         paste! {
@@ -405,6 +409,7 @@ macro_rules! builder {
     }
 }
 
+#[cfg(any(feature = "server", feature = "macros"))]
 builder! {
     ServerCapabilities {
         experimental: ExperimentalCapabilities,
@@ -418,6 +423,7 @@ builder! {
     }
 }
 
+#[cfg(any(feature = "server", feature = "macros"))]
 impl<
     const E: bool,
     const EXT: bool,
@@ -436,6 +442,7 @@ impl<
     }
 }
 
+#[cfg(any(feature = "server", feature = "macros"))]
 impl<
     const E: bool,
     const EXT: bool,
@@ -454,6 +461,7 @@ impl<
     }
 }
 
+#[cfg(any(feature = "server", feature = "macros"))]
 impl<
     const E: bool,
     const EXT: bool,
@@ -479,6 +487,7 @@ impl<
     }
 }
 
+#[cfg(any(feature = "server", feature = "macros"))]
 builder! {
     ClientCapabilities{
         experimental: ExperimentalCapabilities,
@@ -490,6 +499,7 @@ builder! {
     }
 }
 
+#[cfg(any(feature = "server", feature = "macros"))]
 impl<const E: bool, const EXT: bool, const S: bool, const EL: bool, const TASKS: bool>
     ClientCapabilitiesBuilder<ClientCapabilitiesBuilderState<E, EXT, true, S, EL, TASKS>>
 {
@@ -501,6 +511,7 @@ impl<const E: bool, const EXT: bool, const S: bool, const EL: bool, const TASKS:
     }
 }
 
+#[cfg(any(feature = "server", feature = "macros"))]
 impl<const E: bool, const EXT: bool, const R: bool, const EL: bool, const TASKS: bool>
     ClientCapabilitiesBuilder<ClientCapabilitiesBuilderState<E, EXT, R, true, EL, TASKS>>
 {
@@ -521,7 +532,7 @@ impl<const E: bool, const EXT: bool, const R: bool, const EL: bool, const TASKS:
     }
 }
 
-#[cfg(feature = "elicitation")]
+#[cfg(all(feature = "elicitation", any(feature = "server", feature = "macros")))]
 impl<const E: bool, const EXT: bool, const R: bool, const S: bool, const TASKS: bool>
     ClientCapabilitiesBuilder<ClientCapabilitiesBuilderState<E, EXT, R, S, true, TASKS>>
 {
@@ -539,6 +550,7 @@ impl<const E: bool, const EXT: bool, const R: bool, const S: bool, const TASKS:
 }
 
 #[cfg(test)]
+#[cfg(any(feature = "server", feature = "macros"))]
 mod test {
     use super::*;
     #[test]

crates/rmcp/src/model/tool.rs

@@ -1,5 +1,6 @@
 use std::{borrow::Cow, sync::Arc};
 
+#[cfg(feature = "server")]
 use schemars::JsonSchema;
 /// Tools represent a routine that a server can execute
 /// Tool calls represent requests from the client to execute one
@@ -240,6 +241,7 @@ impl Tool {
     /// # Panics
     ///
     /// Panics if the generated schema does not have root type "object" as required by MCP specification.
+    #[cfg(feature = "server")]
     pub fn with_output_schema<T: JsonSchema + 'static>(mut self) -> Self {
         let schema = crate::handler::server::tool::schema_for_output::<T>()
             .unwrap_or_else(|e| panic!("Invalid output schema for tool '{}': {}", self.name, e));
@@ -248,6 +250,7 @@ impl Tool {
     }
 
     /// Set the input schema using a type that implements JsonSchema
+    #[cfg(feature = "server")]
     pub fn with_input_schema<T: JsonSchema + 'static>(mut self) -> Self {
         self.input_schema = crate::handler::server::tool::schema_for_type::<T>();
         self

crates/rmcp/src/service.rs

@@ -1,12 +1,14 @@
 use futures::{FutureExt, future::BoxFuture};
 use thiserror::Error;
 
+#[cfg(feature = "server")]
+use crate::model::ServerJsonRpcMessage;
 use crate::{
     error::ErrorData as McpError,
     model::{
         CancelledNotification, CancelledNotificationParam, Extensions, GetExtensions, GetMeta,
         JsonRpcError, JsonRpcMessage, JsonRpcNotification, JsonRpcRequest, JsonRpcResponse, Meta,
-        NumberOrString, ProgressToken, RequestId, ServerJsonRpcMessage,
+        NumberOrString, ProgressToken, RequestId,
     },
     transport::{DynamicTransportError, IntoTransport, Transport},
 };