diff --git a/src/tools/new.ts b/src/tools/new.ts
index 6c11f9f..f45451e 100644
--- a/src/tools/new.ts
+++ b/src/tools/new.ts
@@ -43,11 +43,15 @@ export default defineTool({
 
     const isPublic = isPublicArg !== false
     const moduleName = name.replace(/-/g, "_")
+    const modulePath = join(dir, `${moduleName}.py`)
 
     if (existsSync(dir)) {
       if (!existsSync(ep.mainPath)) {
         return error(`Error: path already exists at ${dir}, but it is not a valid endpoint (__main__.py is missing)`)
       }
+      if (!existsSync(modulePath)) {
+        return error(`Error: path already exists at ${dir}, but it is not a valid endpoint (module file ${moduleName}.py is missing)`)
+      }
 
       const existingMain = readFileSync(ep.mainPath, "utf-8")
       const existingPublic = existingMain.match(/^#--web\s+(true|false)\s*$/m)?.[1]
@@ -92,7 +96,7 @@ def main(args):
 `
 
     writeFileSync(join(dir, "__main__.py"), mainPy)
-    writeFileSync(join(dir, `${moduleName}.py`), modulePy)
+    writeFileSync(modulePath, modulePy)
 
     return text(`Created endpoint at /api/my/${pkg}/${name}\nFiles:\n  ${dir}/__main__.py\n  ${dir}/${moduleName}.py`)
   },
diff --git a/tests/secrets.test.ts b/tests/secrets.test.ts
index 92390eb..6014f75 100644
--- a/tests/secrets.test.ts
+++ b/tests/secrets.test.ts
@@ -304,6 +304,12 @@ test("action_new reports incompatible existing paths as MCP errors", () => {
     assert.equal(incomplete.isError, true)
     assert.match(resultText(incomplete), /not a valid endpoint/)
 
+    actionNew.handler({ endpoint: "v1/missing-module", public: true })
+    rmSync("packages/v1/missing-module/missing_module.py")
+    const missingModule = actionNew.handler({ endpoint: "v1/missing-module", public: true })
+    assert.equal(missingModule.isError, true)
+    assert.match(resultText(missingModule), /module file missing_module\.py is missing/)
+
     actionNew.handler({ endpoint: "v1/private-action", public: false })
     const visibilityConflict = actionNew.handler({ endpoint: "v1/private-action", public: true })
     assert.equal(visibilityConflict.isError, true)