Improve claude tools (#36538)

- Return unified diff from `Edit` tool so model can see the final state
- Format on save if enabled
- Provide `Write` tool
- Disable `MultiEdit` tool
- Better prompting

Release Notes:

- N/A

crates/context_server/src/listener.rs

@@ -14,6 +14,7 @@ use serde::de::DeserializeOwned;
 use serde_json::{json, value::RawValue};
 use smol::stream::StreamExt;
 use std::{
+    any::TypeId,
     cell::RefCell,
     path::{Path, PathBuf},
     rc::Rc,
@@ -87,18 +88,26 @@ impl McpServer {
         settings.inline_subschemas = true;
         let mut generator = settings.into_generator();
 
-        let output_schema = generator.root_schema_for::<T::Output>();
-        let unit_schema = generator.root_schema_for::<T::Output>();
+        let input_schema = generator.root_schema_for::<T::Input>();
+
+        let description = input_schema
+            .get("description")
+            .and_then(|desc| desc.as_str())
+            .map(|desc| desc.to_string());
+        debug_assert!(
+            description.is_some(),
+            "Input schema struct must include a doc comment for the tool description"
+        );
 
         let registered_tool = RegisteredTool {
             tool: Tool {
                 name: T::NAME.into(),
-                description: Some(tool.description().into()),
-                input_schema: generator.root_schema_for::<T::Input>().into(),
-                output_schema: if output_schema == unit_schema {
+                description,
+                input_schema: input_schema.into(),
+                output_schema: if TypeId::of::<T::Output>() == TypeId::of::<()>() {
                     None
                 } else {
-                    Some(output_schema.into())
+                    Some(generator.root_schema_for::<T::Output>().into())
                 },
                 annotations: Some(tool.annotations()),
             },
@@ -399,8 +408,6 @@ pub trait McpServerTool {
 
     const NAME: &'static str;
 
-    fn description(&self) -> &'static str;
-
     fn annotations(&self) -> ToolAnnotations {
         ToolAnnotations {
             title: None,
@@ -418,6 +425,7 @@ pub trait McpServerTool {
     ) -> impl Future<Output = Result<ToolResponse<Self::Output>>>;
 }
 
+#[derive(Debug)]
 pub struct ToolResponse<T> {
     pub content: Vec<ToolResponseContent>,
     pub structured_content: T,

crates/context_server/src/types.rs

@@ -711,6 +711,16 @@ pub enum ToolResponseContent {
     Resource { resource: ResourceContents },
 }
 
+impl ToolResponseContent {
+    pub fn text(&self) -> Option<&str> {
+        if let ToolResponseContent::Text { text } = self {
+            Some(text)
+        } else {
+            None
+        }
+    }
+}
+
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct ListToolsResponse {