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# CustomSkillsSkill

> A meta-skill that registers user-defined tools from configuration.

[add-skill]: /docs/server-sdks/reference/typescript/agents/agent-base/add-skill

A meta-skill that registers user-defined tools from configuration. Define
tools with names, descriptions, parameters, and JavaScript handler code
without writing skill classes.

**Class:** `CustomSkillsSkill`

**Tools:** Dynamically created from the `tools` array

**Env vars:** `SWML_ALLOW_CUSTOM_HANDLER_CODE` must be set to `"true"` to enable handler execution.

**`tools`** `Record<string, unknown>[]`

Array of custom tool definitions. Each object has:

* `name` (string, required) -- Unique tool name.
* `description` (string, required) -- Tool description shown to the AI.
* `handler_code` (string, required) -- JavaScript function body. Receives `(args, rawData, FunctionResult)` as arguments. Must return a `FunctionResult`, string, or object.
* `parameters` (array, optional) -- Parameter definitions: `[{ name, type, description, required? }]`.
* `required` (string\[], optional) -- Array of required parameter names.
* `prompt_description` (string, optional) -- Description to include in the prompt section.
* `secure` (boolean, optional) -- Whether to mark the tool as secure.
* `fillers` (object, optional) -- Filler phrases keyed by language.

---

**`prompt_title`** `string` — default: Custom Tools

Custom title for the prompt section.

---

**`prompt_body`** `string`

Custom body text for the prompt section.

---

```typescript {6-14}
import { AgentBase, CustomSkillsSkill } from '@signalwire/sdk';

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

await agent.addSkill(new CustomSkillsSkill({
  tools: [
    {
      name: 'greet_user',
      description: 'Greet the user by name.',
      parameters: [
        { name: 'name', type: 'string', description: 'The user name', required: true },
      ],
      required: ['name'],
      handler_code: 'return new FunctionResult("Hello, " + args.name + "! Welcome.");',
    },
  ],
}));

agent.run();
```

> A meta-skill that registers user-defined tools from configuration.