Agent Config: Choose a Model

What it is#

agent.ts is where you configure the agent — most importantly, which model it uses. Eve picks a sensible default, so the file is optional until you want control.

Why you'd care#

Different tasks want different models (cheap vs. capable). agent.ts is the one place to set that, plus runtime options via the AI Gateway.

Before#

You rely on Eve's default model and can't tell which one is answering.

After#

import { defineAgent } from "eve";

export default defineAgent({
  model: "openai/gpt-5.4-mini",
});

Eve now routes calls through the chosen model. Runtime options (timeouts, retries, streaming) live here too, powered by the AI Gateway.

Do it yourself#

1. Create agent/agent.ts and export default defineAgent({ model: "openai/gpt-5.4-mini" }).
2. Run eve dev and confirm responses still work.
3. Swap the model string and re-run to feel the difference.

Gotchas#

• agent.ts is optional — only add it when you want to override the default.
• The model string format follows the AI Gateway convention (provider/model).

Recap#

agent.ts + defineAgent is your control panel: choose the model and tune the runtime. Next, we give the agent something to do — tools.