feat: move shell efficiency guidelines to tool description (#18614)

evals/shell-efficiency.eval.ts

@@ -0,0 +1,110 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, expect } from 'vitest';
+import { evalTest } from './test-helper.js';
+
+describe('Shell Efficiency', () => {
+  const getCommand = (call: any): string | undefined => {
+    let args = call.toolRequest.args;
+    if (typeof args === 'string') {
+      try {
+        args = JSON.parse(args);
+      } catch (e) {
+        // Ignore parse errors
+      }
+    }
+    return typeof args === 'string' ? args : (args as any)['command'];
+  };
+
+  evalTest('ALWAYS_PASSES', {
+    name: 'should use --silent/--quiet flags when installing packages',
+    prompt: 'Install the "lodash" package using npm.',
+    assert: async (rig) => {
+      const toolCalls = rig.readToolLogs();
+      const shellCalls = toolCalls.filter(
+        (call) => call.toolRequest.name === 'run_shell_command',
+      );
+
+      const hasEfficiencyFlag = shellCalls.some((call) => {
+        const cmd = getCommand(call);
+        return (
+          cmd &&
+          cmd.includes('npm install') &&
+          (cmd.includes('--silent') ||
+            cmd.includes('--quiet') ||
+            cmd.includes('-q'))
+        );
+      });
+
+      expect(
+        hasEfficiencyFlag,
+        `Expected agent to use efficiency flags for npm install. Commands used: ${shellCalls
+          .map(getCommand)
+          .join(', ')}`,
+      ).toBe(true);
+    },
+  });
+
+  evalTest('ALWAYS_PASSES', {
+    name: 'should use --no-pager with git commands',
+    prompt: 'Show the git log.',
+    assert: async (rig) => {
+      const toolCalls = rig.readToolLogs();
+      const shellCalls = toolCalls.filter(
+        (call) => call.toolRequest.name === 'run_shell_command',
+      );
+
+      const hasNoPager = shellCalls.some((call) => {
+        const cmd = getCommand(call);
+        return cmd && cmd.includes('git') && cmd.includes('--no-pager');
+      });
+
+      expect(
+        hasNoPager,
+        `Expected agent to use --no-pager with git. Commands used: ${shellCalls
+          .map(getCommand)
+          .join(', ')}`,
+      ).toBe(true);
+    },
+  });
+
+  evalTest('ALWAYS_PASSES', {
+    name: 'should NOT use efficiency flags when enableShellOutputEfficiency is disabled',
+    params: {
+      settings: {
+        tools: {
+          shell: {
+            enableShellOutputEfficiency: false,
+          },
+        },
+      },
+    },
+    prompt: 'Install the "lodash" package using npm.',
+    assert: async (rig) => {
+      const toolCalls = rig.readToolLogs();
+      const shellCalls = toolCalls.filter(
+        (call) => call.toolRequest.name === 'run_shell_command',
+      );
+
+      const hasEfficiencyFlag = shellCalls.some((call) => {
+        const cmd = getCommand(call);
+        return (
+          cmd &&
+          cmd.includes('npm install') &&
+          (cmd.includes('--silent') ||
+            cmd.includes('--quiet') ||
+            cmd.includes('-q'))
+        );
+      });
+
+      expect(
+        hasEfficiencyFlag,
+        'Agent used efficiency flags even though enableShellOutputEfficiency was disabled',
+      ).toBe(false);
+    },
+  });
+});