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# ParameterSchema

> Fluent builder that produces the JSON Schema parameters object for a SWAIG tool.

[define-tool]: /docs/server-sdks/reference/typescript/agents/agent-base/define-tool

[define-typed-tool]: /docs/server-sdks/reference/typescript/agents/agent-base/define-typed-tool

`ParameterSchema` is a fluent builder that produces the JSON Schema `parameters`
object for a SWAIG tool. Properties appear in the order you add them, and the
result is identical to the hand-written JSON Schema object. Create one with
`paramSchema()`.

[`defineTool()`][define-tool] and [`defineTypedTool()`][define-typed-tool]
accept the wrapped `{ type: 'object', properties, required }` object this
builder produces, so pass `build()`'s result directly as `parameters`, as in
the example below.

```typescript {1}
import { paramSchema } from '@signalwire/sdk';
```

## **Methods**

Every method except `build()` returns the builder for chaining.

**`property(name, type, description?, extra?)`** `this`

Add a property with an explicit JSON Schema `type` (`string`, `number`,
`integer`, `boolean`, `array`, or `object`). `extra` merges additional JSON
Schema keywords such as `enum`, `pattern`, `format`, or `items` into the
property.

---

**`string(name, description?, extra?)`** `this`

Add a `string` property.

---

**`integer(name, description?, extra?)`** `this`

Add an `integer` property.

---

**`number(name, description?, extra?)`** `this`

Add a `number` property.

---

**`boolean(name, description?, extra?)`** `this`

Add a `boolean` property.

---

**`array(name, items?, description?)`** `this`

Add an `array` property. `items` is the JSON Schema for each element, such as
`{ type: 'string' }`. Omit it for an untyped array.

---

**`enum(name, values, description?, type?)`** `this`

Add a property constrained to a closed set of values, emitted as `enum` in the
order given. `type` defaults to `string`.

---

**`recordFormat(name, description?)`** `this`

Add a `record_call` format property with `enum: ['wav', 'mp3', 'mp4']`.

---

**`recordDirection(name, description?)`** `this`

Add a `record_call` direction property with `enum: ['speak', 'listen', 'both']`.

---

**`tapDirection(name, description?)`** `this`

Add a `tap` direction property with `enum: ['speak', 'hear', 'both']`.

---

**`codec(name, description?)`** `this`

Add a `tap` codec property with `enum: ['PCMU', 'PCMA']`.

---

**`required(...names)`** `this`

Mark already-added properties as required. Names are recorded in the order
given; duplicates are ignored.

---

**`build()`** `ParameterSchemaObject`

Return the plain `{ type: 'object', properties, required? }` object. `required`
is present only when at least one property was marked required.

---

## **Constants**

The closed sets behind the typed helpers are exported as `as const` arrays,
each with a matching union type.

**`RECORD_FORMATS`** `RecordFormat[]`

`['wav', 'mp3', 'mp4']`

---

**`RECORD_DIRECTIONS`** `RecordDirection[]`

`['speak', 'listen', 'both']`

---

**`TAP_DIRECTIONS`** `TapDirection[]`

`['speak', 'hear', 'both']`

---

**`TAP_CODECS`** `TapCodec[]`

`['PCMU', 'PCMA']`

---

## **Example**

```typescript {5-10,15}
import { AgentBase, FunctionResult, paramSchema } from '@signalwire/sdk';

const agent = new AgentBase({ name: 'dispatch', route: '/dispatch' });

const params = paramSchema()
  .string('pickup', 'Street address for the pickup')
  .enum('vehicle', ['sedan', 'van', 'wheelchair'], 'Vehicle type')
  .integer('passengers', 'Number of riders')
  .required('pickup', 'vehicle')
  .build();

agent.defineTool({
  name: 'book_ride',
  description: 'Book a taxi for the caller',
  parameters: params,
  handler: async (args) => {
    return new FunctionResult(`Booked a ${args.vehicle} to ${args.pickup}.`);
  },
});
```

> Fluent builder that produces the JSON Schema parameters object for a SWAIG tool.