> ## Documentation Index
> Fetch the complete documentation index at: https://www.adaline.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# FunctionSchema

# FunctionSchema

Defines the JSON Schema for a tool or function that an LLM can invoke via function calling.

## Import

```typescript theme={null}
import type { FunctionSchema } from '@adaline/api';
```

## Definition

```typescript theme={null}
interface FunctionSchema {
  name: string;
  description: string;
  parameters: any;
  strict?: boolean | null;
}
```

***

## Fields

| Field         | Type              | Description                                                                                                                                                    |
| ------------- | ----------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `name`        | `string`          | Function name. Must match `^[a-zA-Z0-9_]{1,64}$` — alphanumeric and underscores only, 1–64 characters.                                                         |
| `description` | `string`          | Human-readable description of what the function does. Maximum 4096 characters. The LLM uses this to decide when to call the function.                          |
| `parameters`  | `any`             | A JSON Schema object describing the function's input parameters. Typically an object schema with `properties` and `required`.                                  |
| `strict`      | `boolean \| null` | When `true`, the LLM must produce arguments that strictly conform to the `parameters` schema. When `false` or `null`, the LLM may produce approximate matches. |

***

## Usage

### Basic function schema

```typescript theme={null}
import type { FunctionSchema } from '@adaline/api';

const getWeather: FunctionSchema = {
  name: 'get_weather',
  description: 'Get the current weather for a given city',
  parameters: {
    type: 'object',
    properties: {
      city: {
        type: 'string',
        description: 'City name (e.g., "San Francisco")',
      },
      units: {
        type: 'string',
        enum: ['celsius', 'fahrenheit'],
        default: 'celsius',
        description: 'Temperature units',
      },
    },
    required: ['city'],
  },
  strict: true,
};
```

### Complete tool definition

`FunctionSchema` is used inside a [`ToolFunction`](/docs/reference/sdk/v2/typescript/types/ToolFunction) definition:

```typescript theme={null}
import type { ToolFunction, FunctionSchema } from '@adaline/api';

const schema: FunctionSchema = {
  name: 'search_database',
  description: 'Search the internal knowledge base for relevant documents',
  parameters: {
    type: 'object',
    properties: {
      query: {
        type: 'string',
        description: 'Natural language search query',
      },
      limit: {
        type: 'number',
        description: 'Maximum number of results to return',
        default: 10,
      },
      filters: {
        type: 'object',
        properties: {
          category: { type: 'string' },
          dateAfter: { type: 'string', format: 'date' },
        },
      },
    },
    required: ['query'],
  },
};

const tool: ToolFunction = {
  type: 'function',
  definition: { schema },
};
```

### JSON representation

```json theme={null}
{
  "name": "get_weather",
  "description": "Get the current weather for a given city",
  "parameters": {
    "type": "object",
    "properties": {
      "city": { "type": "string", "description": "City name" },
      "units": { "type": "string", "enum": ["celsius", "fahrenheit"] }
    },
    "required": ["city"]
  },
  "strict": true
}
```

***

## See Also

* [ToolFunction](/docs/reference/sdk/v2/typescript/types/ToolFunction) — wraps `FunctionSchema` inside a tool definition