diff --git a/crates/openpencil-desktop/src/mcp_serve.rs b/crates/openpencil-desktop/src/mcp_serve.rs
index d033bf33a..8a965f070 100644
--- a/crates/openpencil-desktop/src/mcp_serve.rs
+++ b/crates/openpencil-desktop/src/mcp_serve.rs
@@ -369,9 +369,9 @@ const TOOL_SCHEMAS: &[&str] = &[
     // --- write tools ---
     r##"{"name":"set_variable_color","description":"Set a Color-kind variable's value.","inputSchema":{"type":"object","properties":{"name":{"type":"string"},"hex":{"type":"string","description":"#rgb / #rrggbb / #rrggbbaa"}},"required":["name","hex"]}}"##,
     r#"{"name":"batch_design","description":"Insert N leaf nodes on the active page in one atomic shot. nodes_json must be a JSON array string of {kind,name,x,y,width,height,fill_hex?} descriptors.","inputSchema":{"type":"object","properties":{"nodes_json":{"type":"string","description":"JSON array of node descriptors"}},"required":["nodes_json"]}}"#,
-    r#"{"name":"design_skeleton","description":"Layered design workflow phase 1: insert structural scaffolding. Same wire shape as batch_design; response carries phase=skeleton so the client can phase its prompting.","inputSchema":{"type":"object","properties":{"nodes_json":{"type":"string","description":"JSON array of node descriptors"}},"required":["nodes_json"]}}"#,
-    r#"{"name":"design_content","description":"Layered design workflow phase 2: fill content into the scaffold. Same wire shape as batch_design; response carries phase=content.","inputSchema":{"type":"object","properties":{"nodes_json":{"type":"string","description":"JSON array of node descriptors"}},"required":["nodes_json"]}}"#,
-    r#"{"name":"design_refine","description":"Layered design workflow phase 3: polish details. Same wire shape as batch_design; response carries phase=refine.","inputSchema":{"type":"object","properties":{"nodes_json":{"type":"string","description":"JSON array of node descriptors"}},"required":["nodes_json"]}}"#,
+    r#"{"name":"design_skeleton","description":"Layered design workflow phase 1: insert structural scaffolding. Apply behavior is identical to batch_design today (phase is metadata only); the response carries phase=skeleton so the client can phase its prompting. A future patch may add per-phase apply semantics.","inputSchema":{"type":"object","properties":{"nodes_json":{"type":"string","description":"JSON array of node descriptors"}},"required":["nodes_json"]}}"#,
+    r#"{"name":"design_content","description":"Layered design workflow phase 2: fill content into the scaffold. Apply behavior is identical to batch_design today (phase is metadata only); the response carries phase=content. A future patch may add per-phase apply semantics.","inputSchema":{"type":"object","properties":{"nodes_json":{"type":"string","description":"JSON array of node descriptors"}},"required":["nodes_json"]}}"#,
+    r#"{"name":"design_refine","description":"Layered design workflow phase 3: polish details. Apply behavior is identical to batch_design today (phase is metadata only); the response carries phase=refine. A future patch may add per-phase apply semantics.","inputSchema":{"type":"object","properties":{"nodes_json":{"type":"string","description":"JSON array of node descriptors"}},"required":["nodes_json"]}}"#,
     r#"{"name":"set_variable_number","description":"Set a Number-kind variable's value (decimal, may be negative or fractional).","inputSchema":{"type":"object","properties":{"name":{"type":"string"},"value":{"type":"string"}},"required":["name","value"]}}"#,
     r#"{"name":"set_variable_string","description":"Set a String-kind variable's value (free-form text).","inputSchema":{"type":"object","properties":{"name":{"type":"string"},"value":{"type":"string"}},"required":["name","value"]}}"#,
     r#"{"name":"set_variable_boolean","description":"Set a Boolean-kind variable's value (\"true\" or \"false\").","inputSchema":{"type":"object","properties":{"name":{"type":"string"},"value":{"type":"string","enum":["true","false"]}},"required":["name","value"]}}"#,
@@ -430,6 +430,16 @@ mod tests {
     #[test]
     fn tools_list_response_includes_all_twenty_one_tools() {
         let r = tools_list_response("3");
+        // Exact-count assertion: any tool added without
+        // updating this test will trip the count first. Codex
+        // stop-gate: previous `contains`-only checks would have
+        // silently passed if a new tool slipped into TOOL_SCHEMAS
+        // without being added to the list below.
+        assert_eq!(
+            TOOL_SCHEMAS.len(),
+            21,
+            "tools/list catalog count must match the registered tools — add the new tool to this test"
+        );
         for name in [
             "get_document_info",
             "get_selection",