Loop Control: stopWhen

Demonstrate ToolLoopAgent loop control with stopWhen. Covers stepCountIs, hasToolCall, combined conditions, and a custom StopCondition with step timeline visualization.

Loading preview…

Problems solved

Technical challenges this implementation handles out of the box.

Stop agent loops with stepCountIs
Halt when a specific tool is called via hasToolCall
Combine multiple stopWhen conditions
Implement custom StopCondition logic over step history

Use cases

Products and workflows this pattern is designed to support.

Budgeting agent steps in long tool loops
Stopping when a completion tool fires
Preventing runaway tool-calling agents
Visualizing step timelines for loop control

Setup

Requirements, wiring steps, and what this pattern adds to your project.

Getting started

Pick how you want to pull this pattern in — then wire env vars and routes the same way.

1
Install from the preview toolbar
Copy the install command above and run it in your project — Pro patterns include a short-lived token.
2
Add environment variables to .env.local
OPENAI_API_KEY
3
Point client fetches at your API routes
Replace preview `/view/.../api/...` paths with `/api/...` in the installed files.
4
Customize the agent and tool files
Adapt prompts, tools, and stop conditions for your product — Copy for AI in the toolbar helps seed that work.
5
Run your dev server and open the pattern route
Install dependencies if needed, then start the app and verify responses.

Environment variables

OPENAI_API_KEYGet key

Capabilities

AI SDK APIs

ToolLoopAgentstopWhenstepCountIshasToolCallStopConditiontoolgateway

Providers

OpenAI

Files added

11 files

app/page.tsx
app/layout.tsx
app/api/loop-control/route.ts
components/loop-control-demo.tsx
components/step-result-display.tsx
lib/stop-mode-config.ts
lib/stop-agents.ts
lib/infer-stop-reason.ts
tools/research.ts
tools/finalize.ts
README.md

Dependencies

13 total

npm packages

AISDKlucide-reactNext.jsReactZod

Registry components

alertbadgebuttoncardcollapsibleinputskeletontabs

Critical files

lib/stop-agents.ts
Core pattern: createLoopControlAgent(mode) returns ToolLoopAgent instances with stepCountIs, hasToolCall, combined stopWhen array, and custom StopCondition.
lib/infer-stop-reason.ts
Maps GenerateTextResult steps to a human-readable explanation of which stopWhen condition likely terminated the loop.
loop-control/route.ts
API route accepting prompt + mode, runs agent.generate(), returns step timeline and stopReason metadata.
tools/research.ts
Demo research tool that keeps the agent loop running across multiple steps.
tools/finalize.ts
Completion tool used with hasToolCall('finalize') stop condition demonstrations.