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Tools let your agents trigger application code (search, internal APIs, business logic…). AI Kit registers them on the agent and injects them into every generate or stream call.

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Register default tools

import { Agent, google } from "@ai_kit/core";

const assistant = new Agent({
  name: "life-assistant",
  instructions: "Lifestyle assistant",
  model: google("gemini-2.5-flash"),
  tools: {
    google_search: google.tools.googleSearch({}),
  },
  loopTools: true,
  maxStepTools: 15,
});

await assistant.generate({ prompt: "What’s the weather in Paris?" });
  • The tools option exposes tools for every call.
  • loopTools and maxStepTools defined on the agent act as defaults.
  • You can override any of them per call (agent.generate({ tools, loopTools, maxStepTools })).

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Automatic tool loop

When loopTools is enabled and at least one tool is available, AI Kit orchestrates the loop: after each toolCall, the corresponding tool executes and the conversation resumes until a final answer is produced. The result includes a loopTool flag for quick DX inspection. 
const result = await assistant.generate({
  prompt: "Find the workflow documentation for the tool loop feature.",
  loopTools: true,
});

if (result.loopTool) {
  console.log("Tools were executed during the conversation.");
}

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Control knobs

  • loopTools?: boolean – enable or disable the loop (disabled by default).
  • maxStepTools?: number – cap the total amount of tool executions (default: 20).
  • Override both on individual calls when you need a specific behaviour.
await assistant.generate({
  prompt: "Reply without executing any tool.",
  loopTools: false,
});

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Recommendations

  • Prefix tool IDs (search.customer, support.lookup) to simplify monitoring.
  • Lower maxStepTools when a tool can trigger expensive side effects.
  • Log toolCalls in your observability stack to audit model decisions.