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# registerVerbHandler

> Register custom verb handlers for specialized SWML verb processing.

[ref-addverb]: /docs/server-sdks/reference/typescript/agents/swml-service/add-verb

Register a custom verb handler for specialized validation and configuration of
a SWML verb. When a verb with a registered handler is added via
[`addVerb()`][ref-addverb], the handler's
`validateConfig()` method is used instead of generic schema validation.

> **Tip**
>
> Custom verb handlers are useful when a verb has complex validation rules that
> go beyond JSON Schema checks -- for example, mutually exclusive parameters or
> conditional requirements.

## **Parameters**

**`handler`** `SWMLVerbHandler` — required

An object implementing the `SWMLVerbHandler` interface. Must implement three
methods:

* `getVerbName(): string` -- returns the verb name this handler manages
* `validateConfig(config): [boolean, string[]]` -- returns `[isValid, errors]`
* `buildConfig(opts): Record<string, unknown>` -- returns a configuration object

---

## **Returns**

`void`

## **Example**

```typescript {21}
import { SWMLService } from '@signalwire/sdk';
import type { SWMLVerbHandler } from '@signalwire/sdk';

const customHandler: SWMLVerbHandler = {
  getVerbName() {
    return 'my_verb';
  },
  validateConfig(config: Record<string, unknown>) {
    const errors: string[] = [];
    if (!('target' in config)) {
      errors.push("Missing required field 'target'");
    }
    return [errors.length === 0, errors];
  },
  buildConfig(opts: Record<string, unknown>) {
    return { target: opts.target };
  },
};

const service = new SWMLService({ name: 'custom-service' });
service.registerVerbHandler(customHandler);

// Now addVerb will use the custom handler for validation
service.addVerb('my_verb', { target: 'https://example.com' });
console.log(service.renderDocument());
```

> Register custom verb handlers for specialized SWML verb processing.