fix: strip schema titles via schemars SchemaSettings transform

crates/forge_domain/src/agent.rs

@@ -289,7 +289,8 @@ impl From<Agent> for ToolDefinition {
         ToolDefinition {
             name,
             description,
-            input_schema: schemars::schema_for!(crate::AgentInput),
+            input_schema: crate::tool_schema_generator()
+                .into_root_schema_for::<crate::AgentInput>(),
         }
     }
 }

crates/forge_domain/src/tools/catalog.rs

@@ -866,6 +866,7 @@ impl ToolCatalog {
             .with(|s| {
                 s.meta_schema = None;
                 s.inline_subschemas = true;
+                s.transforms.push(Box::new(crate::RemoveSchemaTitles));
             })
             .into_generator();
 

crates/forge_domain/src/tools/definition/tool_definition.rs

@@ -1,31 +1,158 @@
 use derive_setters::Setters;
 use schemars::Schema;
+use schemars::generate::SchemaGenerator;
+use schemars::transform::{Transform, transform_subschemas};
 use serde::{Deserialize, Serialize};
 
 use crate::ToolName;
 
+/// A schemars [`Transform`] that recursively removes the `title` field from
+/// every schema node.
+///
+/// Rust type names are emitted as `title` by the `JsonSchema` derive. These
+/// are internal implementation details and must not be forwarded to LLM
+/// provider APIs.
+#[derive(Debug, Clone, Default)]
+pub struct RemoveSchemaTitles;
+
+impl Transform for RemoveSchemaTitles {
+    fn transform(&mut self, schema: &mut Schema) {
+        if let Some(map) = schema.as_object_mut() {
+            map.remove("title");
+        }
+
+        transform_subschemas(self, schema);
+    }
+}
+
+/// Returns a [`SchemaGenerator`] whose settings include [`RemoveSchemaTitles`]
+/// as a registered transform.
+///
+/// All schemas produced via this generator will never contain `title` fields,
+/// eliminating the need for any post-hoc stripping.
+pub fn tool_schema_generator() -> SchemaGenerator {
+    schemars::generate::SchemaSettings::default()
+        .with(|s| {
+            s.transforms.push(Box::new(RemoveSchemaTitles));
+        })
+        .into_generator()
+}
+
 ///
 /// Refer to the specification over here:
-/// https://glama.ai/blog/2024-11-25-model-context-protocol-quickstart#server
+/// https://glama.ai/blog/2024-11-25-model-context-protocol-quickstart
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Setters)]
 #[setters(into, strip_option)]
 pub struct ToolDefinition {
     pub name: ToolName,
     pub description: String,
+    #[setters(skip)]
     pub input_schema: Schema,
 }
 
 impl ToolDefinition {
-    /// Create a new ToolDefinition
+    /// Create a new ToolDefinition with an empty input schema.
     pub fn new<N: ToString>(name: N) -> Self {
         ToolDefinition {
             name: ToolName::new(name),
             description: String::new(),
-            input_schema: schemars::schema_for!(()), // Empty input schema
+            input_schema: tool_schema_generator().into_root_schema_for::<()>(),
         }
     }
+
+    /// Sets the input schema.
+    ///
+    /// # Arguments
+    /// * `input_schema` - The JSON schema describing accepted tool input
+    pub fn input_schema(mut self, input_schema: impl Into<Schema>) -> Self {
+        self.input_schema = input_schema.into();
+        self
+    }
 }
 
 pub trait ToolDescription {
     fn description(&self) -> String;
 }
+
+#[cfg(test)]
+mod tests {
+    use pretty_assertions::assert_eq;
+    use schemars::JsonSchema;
+    use serde::Deserialize as SerdeDeserialize;
+
+    use super::*;
+
+    /// A struct with a Rust type name that schemars would emit as `title`.
+    #[derive(SerdeDeserialize, JsonSchema)]
+    #[allow(dead_code)]
+    struct InternalPatchInput {
+        old_string: String,
+        nested: NestedInput,
+    }
+
+    #[derive(SerdeDeserialize, JsonSchema)]
+    #[allow(dead_code)]
+    struct NestedInput {
+        value: String,
+    }
+
+    #[test]
+    fn test_tool_schema_generator_strips_titles() {
+        let r#gen = tool_schema_generator();
+        let actual =
+            serde_json::to_value(r#gen.into_root_schema_for::<InternalPatchInput>()).unwrap();
+
+        assert_eq!(
+            actual.pointer("/title"),
+            None,
+            "root title should be absent"
+        );
+        assert_eq!(
+            actual.pointer("/properties/nested/title"),
+            None,
+            "nested title should be absent"
+        );
+    }
+
+    #[test]
+    fn test_tool_definition_new_has_no_title() {
+        let fixture = ToolDefinition::new("patch");
+        let actual = serde_json::to_value(&fixture.input_schema).unwrap();
+        assert_eq!(actual.pointer("/title"), None);
+    }
+
+    #[test]
+    fn test_tool_definition_round_trip_preserves_no_title() {
+        let r#gen = tool_schema_generator();
+        let schema = r#gen.into_root_schema_for::<InternalPatchInput>();
+        let fixture = ToolDefinition::new("patch")
+            .description("Patch a file")
+            .input_schema(schema);
+
+        // Serialise then deserialise and confirm no title leaks in
+        let json_str = serde_json::to_string(&fixture).unwrap();
+        let roundtripped: ToolDefinition = serde_json::from_str(&json_str).unwrap();
+        let actual = serde_json::to_value(roundtripped.input_schema).unwrap();
+        assert_eq!(actual.pointer("/title"), None);
+        assert_eq!(actual.pointer("/properties/nested/title"), None);
+    }
+
+    #[test]
+    fn test_tool_definition_serialization_has_no_title() {
+        let r#gen = tool_schema_generator();
+        let schema = r#gen.into_root_schema_for::<InternalPatchInput>();
+        let fixture = ToolDefinition {
+            name: ToolName::new("patch"),
+            description: "Patch a file".to_string(),
+            input_schema: schema,
+        };
+        let actual = serde_json::to_value(&fixture).unwrap();
+
+        // Titles must be absent at every level regardless of the schema structure
+        assert_eq!(actual.pointer("/input_schema/title"), None);
+        assert_eq!(
+            actual.pointer("/input_schema/$defs/NestedInput/title"),
+            None
+        );
+    }
+}

crates/forge_domain/src/tools/snapshots/forge_domain__tools__catalog__tests__tool_definition_json.snap

@@ -3,7 +3,6 @@ source: crates/forge_domain/src/tools/catalog.rs
 expression: tools
 ---
 {
-  "title": "FSRead",
   "type": "object",
   "properties": {
     "file_path": {
@@ -42,7 +41,6 @@ expression: tools
   ]
 }
 {
-  "title": "FSWrite",
   "type": "object",
   "properties": {
     "content": {
@@ -64,7 +62,6 @@ expression: tools
   ]
 }
 {
-  "title": "FSSearch",
   "type": "object",
   "properties": {
     "-A": {
@@ -153,7 +150,6 @@ expression: tools
   ]
 }
 {
-  "title": "SemanticSearch",
   "type": "object",
   "properties": {
     "queries": {
@@ -184,7 +180,6 @@ expression: tools
   ]
 }
 {
-  "title": "FSRemove",
   "type": "object",
   "properties": {
     "path": {
@@ -197,7 +192,6 @@ expression: tools
   ]
 }
 {
-  "title": "FSPatch",
   "type": "object",
   "properties": {
     "file_path": {
@@ -225,7 +219,6 @@ expression: tools
   ]
 }
 {
-  "title": "FSMultiPatch",
   "type": "object",
   "properties": {
     "edits": {
@@ -266,7 +259,6 @@ expression: tools
   ]
 }
 {
-  "title": "FSUndo",
   "type": "object",
   "properties": {
     "path": {
@@ -279,7 +271,6 @@ expression: tools
   ]
 }
 {
-  "title": "Shell",
   "type": "object",
   "properties": {
     "command": {
@@ -314,7 +305,6 @@ expression: tools
   ]
 }
 {
-  "title": "NetFetch",
   "description": "Input type for the net fetch tool",
   "type": "object",
   "properties": {
@@ -333,7 +323,6 @@ expression: tools
   ]
 }
 {
-  "title": "Followup",
   "type": "object",
   "properties": {
     "multiple": {
@@ -376,7 +365,6 @@ expression: tools
   ]
 }
 {
-  "title": "PlanCreate",
   "type": "object",
   "properties": {
     "content": {
@@ -399,7 +387,6 @@ expression: tools
   ]
 }
 {
-  "title": "SkillFetch",
   "type": "object",
   "properties": {
     "name": {
@@ -412,7 +399,6 @@ expression: tools
   ]
 }
 {
-  "title": "TodoWrite",
   "type": "object",
   "properties": {
     "todos": {
@@ -449,11 +435,9 @@ expression: tools
   ]
 }
 {
-  "title": "TodoRead",
   "type": "object"
 }
 {
-  "title": "TaskInput",
   "description": "Input structure for the Task tool - delegates work to specialized agents",
   "type": "object",
   "properties": {