refactor: unify IntoCallToolResult Result impls (#787)

crates/rmcp/src/handler/server/tool.rs

@@ -85,20 +85,29 @@ impl<T: IntoContents> IntoCallToolResult for T {
     }
 }
 
-impl<T: IntoContents, E: IntoContents> IntoCallToolResult for Result<T, E> {
+impl IntoCallToolResult for CallToolResult {
     fn into_call_tool_result(self) -> Result<CallToolResult, crate::ErrorData> {
-        match self {
+        Ok(self)
-            Ok(value) => Ok(CallToolResult::success(value.into_contents())),
-            Err(error) => Ok(CallToolResult::error(error.into_contents())),
-        }
     }
 }
 
-impl<T: IntoCallToolResult> IntoCallToolResult for Result<T, crate::ErrorData> {
+impl IntoCallToolResult for crate::ErrorData {
+    fn into_call_tool_result(self) -> Result<CallToolResult, crate::ErrorData> {
+        Err(self)
+    }
+}
+
+impl<T: IntoCallToolResult, E: IntoCallToolResult> IntoCallToolResult for Result<T, E> {
     fn into_call_tool_result(self) -> Result<CallToolResult, crate::ErrorData> {
         match self {
             Ok(value) => value.into_call_tool_result(),
-            Err(error) => Err(error),
+            Err(error) => match error.into_call_tool_result() {
+                Ok(mut result) => {
+                    result.is_error = Some(true);
+                    Ok(result)
+                }
+                Err(e) => Err(e),
+            },
         }
     }
 }
@@ -139,12 +148,6 @@ where
     }
 }
 
-impl IntoCallToolResult for Result<CallToolResult, crate::ErrorData> {
-    fn into_call_tool_result(self) -> Result<CallToolResult, crate::ErrorData> {
-        self
-    }
-}
-
 pub trait CallToolHandler<S, A> {
     fn call(
         self,

crates/rmcp/src/handler/server/wrapper/json.rs

@@ -3,10 +3,7 @@ use std::borrow::Cow;
 use schemars::JsonSchema;
 use serde::Serialize;
 
-use crate::{
+use crate::{handler::server::tool::IntoCallToolResult, model::CallToolResult};
-    handler::server::tool::IntoCallToolResult,
-    model::{CallToolResult, IntoContents},
-};
 
 /// Json wrapper for structured output
 ///
@@ -41,15 +38,3 @@ impl<T: Serialize + JsonSchema + 'static> IntoCallToolResult for Json<T> {
         Ok(CallToolResult::structured(value))
     }
 }
-
-// Implementation for Result<Json<T>, E>
-impl<T: Serialize + JsonSchema + 'static, E: IntoContents> IntoCallToolResult
-    for Result<Json<T>, E>
-{
-    fn into_call_tool_result(self) -> Result<CallToolResult, crate::ErrorData> {
-        match self {
-            Ok(value) => value.into_call_tool_result(),
-            Err(error) => Ok(CallToolResult::error(error.into_contents())),
-        }
-    }
-}