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# set_dynamic_config_callback

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

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

[add-per-call-config]: /docs/server-sdks/reference/python/agents/agent-base/add-per-call-config

Set a callback function that runs on every incoming request, receiving an ephemeral
copy of the agent so you can dynamically configure **any** aspect of it -- skills,
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.

> **Only one callback is kept**
>
> A second call replaces the first without warning: the agent still renders valid
> SWML, but whatever the discarded callback configured is absent. To register
> several callbacks that run in order, use
> [`add_per_call_config()`][add-per-call-config].

> **Note**
>
> The `agent` argument passed to the callback is an **ephemeral copy** of the original
> agent. Changes made inside the callback apply only to the current request and do not
> persist across calls.

## **Parameters**

**`callback`** `Callable[[dict, dict, dict, AgentBase], None]` — required

A function with the signature `(query_params, body_params, headers, agent)`.
Use the `agent` argument to call any configuration method:

* `agent.add_skill(...)`
* `agent.add_language(...)`
* `agent.prompt_add_section(...)`
* `agent.set_params(...)`
* `agent.set_global_data(...)`
* `agent.define_tool(...)`

---

## **Returns**

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

## **Example**

```python {13}
from signalwire import AgentBase

agent = AgentBase(name="assistant", route="/assistant")
agent.set_prompt_text("You are a helpful assistant.")

def configure_per_request(query_params, body_params, headers, agent):
    tier = query_params.get("tier", "standard")
    if tier == "premium":
        agent.add_skill("web_search")
        agent.set_params({"end_of_speech_timeout": 500})
    agent.set_global_data({"tier": tier})

agent.set_dynamic_config_callback(configure_per_request)
agent.serve()
```

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