fix: omit StructuredOutput from tool intent injection

StructuredOutput is mechanical and its consumers treat the advertised
schema as an exact contract.

Author: elkaix

packages/agent-core/src/loop/tool-intent.ts

@@ -2,8 +2,8 @@ import type { ExecutableTool } from './types';
 
 export const INTENT_FIELD = 'i';
 export const INTENT_MAX_LENGTH = 120;
-/** Tool names excluded from intent injection. Empty today; add names when a tool's intent is self-evident. */
-export const INTENT_OMIT_TOOLS: ReadonlySet<string> = new Set();
+/** Tool names excluded from intent injection. StructuredOutput is mechanical and has an exact schema contract. */
+export const INTENT_OMIT_TOOLS: ReadonlySet<string> = new Set(['StructuredOutput']);
 
 // oxlint-disable-next-line no-control-regex -- model-authored terminal text must not retain escape sequences.
 const ANSI_ESCAPE = /\u001B(?:\[[0-?]*[ -/]*[@-~]|\][^\u0007]*(?:\u0007|$))/gu;

packages/agent-core/test/loop/tool-intent.test.ts

@@ -61,6 +61,11 @@ describe('tool intent schema injection', () => {
     }
   });
 
+  it('returns StructuredOutput unchanged', () => {
+    const tool = makeTool('StructuredOutput');
+    expect(injectIntentIntoTools([tool])[0]).toBe(tool);
+  });
+
   it('returns tools with an intent collision unchanged', () => {
     const tool = makeTool('collision', {
       type: 'object',