Add plan tool feature flag

codex-rs/core/src/features.rs

@@ -32,6 +32,8 @@ pub enum Feature {
     GhostCommit,
     /// Include the view_image tool.
     ViewImageTool,
+    /// Include the plan tool.
+    PlanTool,
     /// Send warnings to the model to correct it on the tool usage.
     ModelWarnings,
     /// Enable the default shell tool.
@@ -280,6 +282,12 @@ pub const FEATURES: &[FeatureSpec] = &[
         stage: Stage::Stable,
         default_enabled: true,
     },
+    FeatureSpec {
+        id: Feature::PlanTool,
+        key: "plan_tool",
+        stage: Stage::Stable,
+        default_enabled: true,
+    },
     FeatureSpec {
         id: Feature::ShellTool,
         key: "shell_tool",

codex-rs/core/src/tools/spec.rs

@@ -22,6 +22,7 @@ pub(crate) struct ToolsConfig {
     pub apply_patch_tool_type: Option<ApplyPatchToolType>,
     pub web_search_request: bool,
     pub include_view_image_tool: bool,
+    pub include_plan_tool: bool,
     pub experimental_supported_tools: Vec<String>,
 }
 
@@ -39,6 +40,7 @@ impl ToolsConfig {
         let include_apply_patch_tool = features.enabled(Feature::ApplyPatchFreeform);
         let include_web_search_request = features.enabled(Feature::WebSearchRequest);
         let include_view_image_tool = features.enabled(Feature::ViewImageTool);
+        let include_plan_tool = features.enabled(Feature::PlanTool);
 
         let shell_type = if !features.enabled(Feature::ShellTool) {
             ConfigShellToolType::Disabled
@@ -65,6 +67,7 @@ impl ToolsConfig {
             apply_patch_tool_type,
             web_search_request: include_web_search_request,
             include_view_image_tool,
+            include_plan_tool,
             experimental_supported_tools: model_family.experimental_supported_tools.clone(),
         }
     }
@@ -1037,8 +1040,10 @@ pub(crate) fn build_specs(
     builder.register_handler("list_mcp_resource_templates", mcp_resource_handler.clone());
     builder.register_handler("read_mcp_resource", mcp_resource_handler);
 
-    builder.push_spec(PLAN_TOOL.clone());
-    builder.register_handler("update_plan", plan_handler);
+    if config.include_plan_tool {
+        builder.push_spec(PLAN_TOOL.clone());
+        builder.register_handler("update_plan", plan_handler);
+    }
 
     if let Some(apply_patch_tool_type) = &config.apply_patch_tool_type {
         match apply_patch_tool_type {
@@ -1413,6 +1418,23 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_gpt_5_defaults_without_plan_tool() {
+        let mut features = Features::with_defaults();
+        features.disable(Feature::PlanTool);
+        assert_model_tools(
+            "gpt-5",
+            &features,
+            &[
+                "shell",
+                "list_mcp_resources",
+                "list_mcp_resource_templates",
+                "read_mcp_resource",
+                "view_image",
+            ],
+        );
+    }
+
     #[test]
     fn test_gpt_5_1_defaults() {
         assert_model_tools(

docs/config.md

@@ -45,6 +45,7 @@ Supported features:
 | `rmcp_client`                         |  false  | Experimental | Enable oauth support for streamable HTTP MCP servers  |
 | `apply_patch_freeform`                |  false  | Beta         | Include the freeform `apply_patch` tool               |
 | `view_image_tool`                     |  true   | Stable       | Include the `view_image` tool                         |
+| `plan_tool`                           |  true   | Stable       | Include the `update_plan` tool                        |
 | `web_search_request`                  |  false  | Stable       | Allow the model to issue web searches                 |
 | `ghost_commit`                        |  false  | Experimental | Create a ghost commit each turn                       |
 | `enable_experimental_windows_sandbox` |  false  | Experimental | Use the Windows restricted-token sandbox              |

docs/example-config.md

@@ -217,6 +217,7 @@ unified_exec = false
 rmcp_client = false
 apply_patch_freeform = false
 view_image_tool = true
+plan_tool = true
 web_search_request = false
 ghost_commit = false
 enable_experimental_windows_sandbox = false