> Fetch clean Markdown by appending `.md` to any page URL under https://signalwire.com/docs or requesting it with the HTTP header `Accept: text/markdown`. The root index at https://signalwire.com/docs/llms.txt lists the available documentation indexes.

# setDynamicConfigCallback

> Set a callback for per-request dynamic agent configuration.

[ref-agentbase]: /docs/server-sdks/reference/typescript/agents/agent-base

Set a callback that runs on every incoming SWML request, receiving an ephemeral copy
of the agent so you can dynamically configure **any** aspect of it -- prompts,
parameters, languages, tools, global data, etc. -- based on the request's query
parameters, body, or headers.

This is the primary mechanism for multi-tenant or per-caller customization.

> **Note**
>
> The `agent` argument is an **ephemeral copy** of the base agent — changes made
> inside the callback apply only to the current request and do not persist to the
> base agent or affect other requests.

## **Parameters**

**`cb`** `DynamicConfigCallback` — required

A function with the signature
`(queryParams: Record<string, string>, bodyParams: Record<string, unknown>, headers: Record<string, string>, agent: AgentBase) => void | Promise<void>`.
Use the `agent` argument to call any configuration method on the ephemeral copy.

---

## **Returns**

[`AgentBase`][ref-agentbase] -- Returns `this` for method chaining.

## **Example**

```typescript {6}
import { AgentBase } from '@signalwire/sdk';

const agent = new AgentBase({ name: 'assistant', route: '/assistant' });
agent.setPromptText('You are a helpful assistant.');

agent.setDynamicConfigCallback(async (queryParams, bodyParams, headers, agentCopy) => {
  const tier = queryParams.tier ?? 'standard';
  if (tier === 'premium') {
    agentCopy.setParams({ end_of_speech_timeout: 500 });
  }
  agentCopy.setGlobalData({ tier });
});

await agent.serve();
```

> Set a callback for per-request dynamic agent configuration.