# Interface: AgentDefinition

## Properties[​](#properties "Direct link to Properties")

### agents?[​](#agents "Direct link to agents?")

```ts
optional agents: Record<string, AgentDefinition>;

```

Sub-agents, exposed as `agent-<key>` tools on this agent.

***

### baseSystemPrompt?[​](#basesystemprompt "Direct link to baseSystemPrompt?")

```ts
optional baseSystemPrompt: BaseSystemPromptOption;

```

Override the plugin's baseSystemPrompt for this agent only.

***

### ephemeral?[​](#ephemeral "Direct link to ephemeral?")

```ts
optional ephemeral: boolean;

```

When true, the thread used for a chat request against this agent is deleted from `ThreadStore` after the stream completes (success or failure). Use for stateless one-shot agents — e.g. autocomplete, where each request is independent and retaining history would both poison future calls and accumulate unbounded state in the default `InMemoryThreadStore`. Defaults to `false`.

***

### instructions[​](#instructions "Direct link to instructions")

```ts
instructions: string;

```

System prompt body. For markdown-loaded agents this is the file body.

***

### maxSteps?[​](#maxsteps "Direct link to maxSteps?")

```ts
optional maxSteps: number;

```

***

### maxTokens?[​](#maxtokens "Direct link to maxTokens?")

```ts
optional maxTokens: number;

```

***

### model?[​](#model "Direct link to model?")

```ts
optional model: 
  | string
  | AgentAdapter
| Promise<AgentAdapter>;

```

Model adapter (or endpoint-name string sugar for `DatabricksAdapter.fromServingEndpoint({ endpointName })`). Optional — falls back to the plugin's `defaultModel`.

***

### name?[​](#name "Direct link to name?")

```ts
optional name: string;

```

Stable identifier for the agent. **Optional and informational** — when the definition is registered via `agents: { foo: def }` (code) or lives at `config/agents/<id>/agent.md` (markdown), the **registry key always wins** and `name` is ignored. The agent will be reachable as `foo` (or `<id>`) regardless of what this field contains.

Set `name` when:

* Running standalone via `runAgent({ agent: def })`, where there is no enclosing key. The runtime uses it for the agent's slot in error messages and OTel spans.
* Building a definition that may be passed to either form and you want a consistent fallback label.

Setting `name` to a value that differs from the registry key is harmless but confusing — prefer keeping them aligned or omitting `name` entirely.

***

### tools?[​](#tools "Direct link to tools?")

```ts
optional tools: 
  | AgentTools
  | AgentToolsFn;

```

Per-agent tool record. Key is the LLM-visible tool-call name.

Accepts either a plain record (for agents that only use inline tools) or a function `(plugins) => Record<string, AgentTool>` that receives the typed [Plugins](./docs/api/appkit/TypeAlias.Plugins.md) map and returns a tool record (for agents that pull tools from registered plugins).

The function is invoked once at agent setup; the result is cached. Don't put per-request logic in there.