diff --git a/packages/cli/src/modules/agents/agents.service.ts b/packages/cli/src/modules/agents/agents.service.ts
index b88c1ecbfef..d66a58ed65c 100644
--- a/packages/cli/src/modules/agents/agents.service.ts
+++ b/packages/cli/src/modules/agents/agents.service.ts
@@ -636,6 +636,20 @@ export class AgentsService {
 		const { agent, agentId, projectId, credentialProvider, nodeToolsEnabled, integrationType } =
 			params;
 
+		// Inject get_environment unconditionally. It surfaces info the model
+		// can't know on its own (current date, instance timezone, day of week)
+		// via a tool call rather than the system prompt — so values that change
+		// per request don't bust system-prompt prompt caching.
+		try {
+			const { createGetEnvironmentTool } = await import('./tools/environment-tool');
+			agent.tool(createGetEnvironmentTool());
+		} catch (toolError) {
+			this.logger.warn('Failed to inject get_environment tool', {
+				agentId,
+				error: toolError instanceof Error ? toolError.message : String(toolError),
+			});
+		}
+
 		// Inject the rich_interaction tool only for platforms that can actually
 		// render its suspend/resume HITL cards. Two gates:
 		//   - A registered integration in ChatIntegrationRegistry. The in-app
diff --git a/packages/cli/src/modules/agents/tools/__tests__/environment-tool.test.ts b/packages/cli/src/modules/agents/tools/__tests__/environment-tool.test.ts
new file mode 100644
index 00000000000..a3c73a22c6f
--- /dev/null
+++ b/packages/cli/src/modules/agents/tools/__tests__/environment-tool.test.ts
@@ -0,0 +1,71 @@
+import { GlobalConfig } from '@n8n/config';
+import { Container } from '@n8n/di';
+import { DateTime, Settings } from 'luxon';
+
+import { createGetEnvironmentTool } from '../environment-tool';
+
+describe('createGetEnvironmentTool', () => {
+	const FIXED_NOW_MS = DateTime.fromISO('2026-05-05T14:32:11.000Z', { zone: 'utc' }).toMillis();
+
+	beforeEach(() => {
+		Settings.now = () => FIXED_NOW_MS;
+		Container.set(GlobalConfig, { generic: { timezone: 'America/New_York' } } as GlobalConfig);
+	});
+
+	afterEach(() => {
+		Settings.now = () => Date.now();
+		Container.reset();
+	});
+
+	function makeCtx() {
+		return {
+			parentTelemetry: undefined,
+		};
+	}
+
+	it('builds a tool with the correct name', () => {
+		const tool = createGetEnvironmentTool().build();
+		expect(tool.name).toBe('get_environment');
+	});
+
+	it('returns now in the instance timezone with offset', async () => {
+		const tool = createGetEnvironmentTool().build();
+
+		const result = (await tool.handler!({}, makeCtx())) as {
+			now: string;
+			timezone: string;
+			dayOfWeek: string;
+		};
+
+		// 14:32:11Z in America/New_York (DST) = 10:32:11-04:00
+		expect(result.now).toBe('2026-05-05T10:32:11.000-04:00');
+		expect(result.timezone).toBe('America/New_York');
+		expect(result.dayOfWeek).toBe('Tuesday');
+	});
+
+	it('reflects a different configured timezone', async () => {
+		Container.set(GlobalConfig, { generic: { timezone: 'Asia/Tokyo' } } as GlobalConfig);
+
+		const tool = createGetEnvironmentTool().build();
+		const result = (await tool.handler!({}, makeCtx())) as {
+			now: string;
+			timezone: string;
+			dayOfWeek: string;
+		};
+
+		// 14:32:11Z in Asia/Tokyo = 23:32:11+09:00
+		expect(result.now).toBe('2026-05-05T23:32:11.000+09:00');
+		expect(result.timezone).toBe('Asia/Tokyo');
+		expect(result.dayOfWeek).toBe('Tuesday');
+	});
+
+	it('reads timezone at handler time, not creation time', async () => {
+		const tool = createGetEnvironmentTool().build();
+
+		// Mutate config after the tool is built; the handler must pick up the change.
+		Container.set(GlobalConfig, { generic: { timezone: 'Europe/London' } } as GlobalConfig);
+
+		const result = (await tool.handler!({}, makeCtx())) as { timezone: string };
+		expect(result.timezone).toBe('Europe/London');
+	});
+});
diff --git a/packages/cli/src/modules/agents/tools/environment-tool.ts b/packages/cli/src/modules/agents/tools/environment-tool.ts
new file mode 100644
index 00000000000..85a3c4078e2
--- /dev/null
+++ b/packages/cli/src/modules/agents/tools/environment-tool.ts
@@ -0,0 +1,28 @@
+import { Tool } from '@n8n/agents';
+import { GlobalConfig } from '@n8n/config';
+import { Container } from '@n8n/di';
+import { DateTime } from 'luxon';
+import { z } from 'zod';
+
+const DESCRIPTION =
+	'Returns runtime info that the LLM cannot know on its own: ' +
+	'current ISO date/time, instance timezone (IANA), and day of week. ' +
+	'Call when reasoning about "today", deadlines, or scheduling.';
+
+export function createGetEnvironmentTool() {
+	return (
+		new Tool('get_environment')
+			.description(DESCRIPTION)
+			.input(z.object({}))
+			// eslint-disable-next-line @typescript-eslint/require-await -- Tool.handler() expects an async callback
+			.handler(async () => {
+				const timezone = Container.get(GlobalConfig).generic.timezone;
+				const now = DateTime.now().setZone(timezone);
+				return {
+					now: now.toISO(),
+					timezone,
+					dayOfWeek: now.weekdayLong,
+				};
+			})
+	);
+}