diff --git a/src/tools/agent-teams/name-validation.test.ts b/src/tools/agent-teams/name-validation.test.ts
index 9e2c70ca..ec68b0e9 100644
--- a/src/tools/agent-teams/name-validation.test.ts
+++ b/src/tools/agent-teams/name-validation.test.ts
@@ -71,8 +71,9 @@ describe("agent-teams name validation", () => {
   test("validates task ids", () => {
     //#then
     expect(validateTaskId("T-123")).toBeNull()
+    expect(validateTaskId("123")).toBe("task_id_invalid")
     expect(validateTaskId("")).toBe("task_id_required")
     expect(validateTaskId("../../etc/passwd")).toBe("task_id_invalid")
-    expect(validateTaskId("a".repeat(129))).toBe("task_id_too_long")
+    expect(validateTaskId(`T-${"a".repeat(127)}`)).toBe("task_id_too_long")
   })
 })
diff --git a/src/tools/agent-teams/name-validation.ts b/src/tools/agent-teams/name-validation.ts
index dcf3fcf1..83e8784e 100644
--- a/src/tools/agent-teams/name-validation.ts
+++ b/src/tools/agent-teams/name-validation.ts
@@ -1,6 +1,6 @@
 const VALID_NAME_RE = /^[A-Za-z0-9_-]+$/
 const MAX_NAME_LENGTH = 64
-const VALID_TASK_ID_RE = /^[A-Za-z0-9_-]+$/
+const VALID_TASK_ID_RE = /^T-[A-Za-z0-9_-]+$/
 const MAX_TASK_ID_LENGTH = 128
 
 function validateName(value: string, label: "team" | "agent"): string | null {