@mastra/rag/dist/docs/references/reference-tools-document-chunker-tool.md

The Retrieval-Augmented Generation (RAG) module contains document processing and embedding utilities.

# createDocumentChunkerTool()

The `createDocumentChunkerTool()` function creates a tool for splitting documents into smaller chunks for efficient processing and retrieval. It supports different chunking strategies and configurable parameters.

## Basic usage

```typescript
import { createDocumentChunkerTool, MDocument } from '@mastra/rag'

const document = new MDocument({
  text: 'Your document content here...',
  metadata: { source: 'user-manual' },
})

const chunker = createDocumentChunkerTool({
  doc: document,
  params: {
    strategy: 'recursive',
    size: 512,
    overlap: 50,
    separator: '\n',
  },
})

const { chunks } = await chunker.execute()
```

## Parameters

**doc** (`MDocument`): The document to be chunked

**params** (`ChunkParams`): Configuration parameters for chunking (Default: `Default chunking parameters`)

### `ChunkParams`

**strategy** (`'recursive'`): The chunking strategy to use (Default: `'recursive'`)

**size** (`number`): Target size of each chunk in tokens/characters (Default: `512`)

**overlap** (`number`): Number of overlapping tokens/characters between chunks (Default: `50`)

**separator** (`string`): Character(s) to use as chunk separator (Default: `'\n'`)

## Returns

**chunks** (`DocumentChunk[]`): Array of document chunks with their content and metadata

## Example with custom parameters

```typescript
const technicalDoc = new MDocument({
  text: longDocumentContent,
  metadata: {
    type: 'technical',
    version: '1.0',
  },
})

const chunker = createDocumentChunkerTool({
  doc: technicalDoc,
  params: {
    strategy: 'recursive',
    size: 1024, // Larger chunks
    overlap: 100, // More overlap
    separator: '\n\n', // Split on double newlines
  },
})

const { chunks } = await chunker.execute()

// Process the chunks
chunks.forEach((chunk, index) => {
  console.log(`Chunk ${index + 1} length: ${chunk.content.length}`)
})
```

## Tool details

The chunker is created as a Mastra tool with the following properties:

- **Tool ID**: `Document Chunker {strategy} {size}`
- **Description**: `Chunks document using {strategy} strategy with size {size} and {overlap} overlap`
- **Input Schema**: Empty object (no additional inputs required)
- **Output Schema**: Object containing the chunks array

## Related

- [MDocument](https://mastra.ai/reference/rag/document)
- [createVectorQueryTool](https://mastra.ai/reference/tools/vector-query-tool)