tools: simplify default tool search text (#27526)

## Why

Default tool search text currently derives identity from both `ToolName`
and `ToolSpec`. For function and namespace specs, this indexes the same
names more than once and also adds a flattened `{namespace}{name}` token
that is not model-visible.

## What changed

- Derive default search text entirely from `ToolSpec` while preserving
names, descriptions, namespace metadata, and recursive schema metadata.
- Keep the default search-text builder private and remove the unused
`ToolName` argument.
- Add coverage for the exact search text generated for a namespaced tool
with nested schema metadata.

## Example

For the `codex_app` namespace and `automation_update` tool (schema terms
omitted):

- Before: `codex_appautomation_update automation update codex_app
codex_app Manage Codex automations. automation_update automation update
...`
- After: `codex_app Manage Codex automations. automation_update
automation update ...`

## Testing

- `just test -p codex-tools`

codex-rs/tools/src/lib.rs

@@ -100,7 +100,6 @@ pub use tool_output::ToolOutput;
 pub use tool_payload::ToolPayload;
 pub use tool_search::ToolSearchEntry;
 pub use tool_search::ToolSearchInfo;
-pub use tool_search::default_tool_search_text;
 pub use tool_spec::ResponsesApiWebSearchFilters;
 pub use tool_spec::ResponsesApiWebSearchUserLocation;
 pub use tool_spec::ToolSpec;

codex-rs/tools/src/tool_executor.rs

@@ -58,7 +58,7 @@ pub trait ToolExecutor<Invocation>: Send + Sync {
 
     fn search_info(&self) -> Option<ToolSearchInfo> {
         let spec = self.spec();
-        ToolSearchInfo::from_tool_spec(&self.tool_name(), spec, /*source_info*/ None)
+        ToolSearchInfo::from_tool_spec(spec, /*source_info*/ None)
     }
 
     fn supports_parallel_tool_calls(&self) -> bool {

codex-rs/tools/src/tool_search.rs

@@ -2,7 +2,6 @@ use crate::JsonSchema;
 use crate::LoadableToolSpec;
 use crate::ResponsesApiNamespaceTool;
 use crate::ResponsesApiTool;
-use crate::ToolName;
 use crate::ToolSearchSourceInfo;
 use crate::ToolSpec;
 use crate::default_namespace_description;
@@ -21,11 +20,10 @@ pub struct ToolSearchInfo {
 
 impl ToolSearchInfo {
     pub fn from_tool_spec(
-        tool_name: &ToolName,
         spec: ToolSpec,
         source_info: Option<ToolSearchSourceInfo>,
     ) -> Option<Self> {
-        let search_text = default_tool_search_text(tool_name, &spec);
+        let search_text = default_tool_search_text(&spec);
         Self::from_spec(search_text, spec, source_info)
     }
 
@@ -67,13 +65,8 @@ impl ToolSearchInfo {
     }
 }
 
-pub fn default_tool_search_text(tool_name: &ToolName, spec: &ToolSpec) -> String {
+fn default_tool_search_text(spec: &ToolSpec) -> String {
     let mut parts = Vec::new();
-    push_search_part(&mut parts, tool_name.to_string());
-    push_search_part(&mut parts, tool_name.name.replace('_', " "));
-    if let Some(namespace) = &tool_name.namespace {
-        push_search_part(&mut parts, namespace.clone());
-    }
 
     match spec {
         ToolSpec::Function(tool) => append_function_search_text(tool, &mut parts),
@@ -137,3 +130,7 @@ fn push_search_part(parts: &mut Vec<String>, part: String) {
         parts.push(part.to_string());
     }
 }
+
+#[cfg(test)]
+#[path = "tool_search_tests.rs"]
+mod tests;

codex-rs/tools/src/tool_search_tests.rs

@@ -0,0 +1,48 @@
+use super::*;
+use pretty_assertions::assert_eq;
+use std::collections::BTreeMap;
+
+#[test]
+fn default_search_text_uses_model_visible_namespace_metadata_once() {
+    let mut schedule_schema = JsonSchema::object(
+        BTreeMap::from([(
+            "timezone".to_string(),
+            JsonSchema::string(Some("IANA timezone.".to_string())),
+        )]),
+        /*required*/ None,
+        /*additional_properties*/ None,
+    );
+    schedule_schema.description = Some("Schedule settings.".to_string());
+    let mut parameters = JsonSchema::object(
+        BTreeMap::from([
+            (
+                "mode".to_string(),
+                JsonSchema::string(Some("Update mode.".to_string())),
+            ),
+            ("schedule".to_string(), schedule_schema),
+        ]),
+        /*required*/ None,
+        /*additional_properties*/ None,
+    );
+    parameters.description = Some("Automation options.".to_string());
+    let spec = ToolSpec::Namespace(crate::ResponsesApiNamespace {
+        name: "codex_app".to_string(),
+        description: "Manage Codex automations.".to_string(),
+        tools: vec![ResponsesApiNamespaceTool::Function(ResponsesApiTool {
+            name: "automation_update".to_string(),
+            description: "Create or update automations.".to_string(),
+            strict: false,
+            defer_loading: None,
+            parameters,
+            output_schema: None,
+        })],
+    });
+
+    let search_info = ToolSearchInfo::from_tool_spec(spec, /*source_info*/ None)
+        .expect("namespace should be searchable");
+
+    assert_eq!(
+        search_info.entry.search_text,
+        "codex_app Manage Codex automations. automation_update automation update Create or update automations. Automation options. mode Update mode. schedule Schedule settings. timezone IANA timezone."
+    );
+}