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

# Anthropic Tool Response Adapter

`AnthropicMessagesToolResponseAdapter` is the default `ToolResponseAdapter` used whenever you pair an agent with the Anthropic Messages adapter. It converts tool outputs into Anthropic `tool_result` blocks and provides a plain-text fallback that hosts can display or log.

## Behavior summary

* **Plain-text rendering:** `to_plain_text` generates concise strings for common response types (`LinkChunk`, `JsonChunk`, `TextChunk`, `FileChunk`, `EmptyChunk`).
* **Chat context updates:** `create_messages` returns a user message containing a `tool_result` block so the model can consume tool output on the next turn.
* **Attachment handling:** Images and PDFs are converted into Anthropic `image` or `document` blocks; unsupported image types fall back to text.
* **Developer logging:** Emits events via `room.developer.log_nowait` to aid debugging when tools are called.

## Response handling

| Response type     | Plain text example            | Notes                                                                                                                                                               |
| ----------------- | ----------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `TextChunk`       | The returned text             | Included as a text block in the `tool_result`.                                                                                                                      |
| `JsonChunk`       | JSON string dump              | Included as a text block in the `tool_result`.                                                                                                                      |
| `FileChunk`       | `filename.ext`                | Images (`image/jpeg`, `image/png`, `image/gif`, `image/webp`) are embedded as Anthropic image blocks; PDFs become `document` blocks; other files fall back to text. |
| `LinkChunk`       | `{ "name": ..., "url": ... }` | Serialized to JSON and included as a text block.                                                                                                                    |
| `EmptyChunk`      | `"ok"`                        | Signals successful execution without additional data.                                                                                                               |
| `RawOutputsChunk` | n/a                           | Passed through directly as Anthropic message blocks, bypassing plain-text conversion.                                                                               |

## Tool use requirements

Anthropic requires tool results to include a `tool_use_id`. The adapter raises an error if the `tool_use` block is missing an `id`.

## Extending or replacing

You can subclass `AnthropicMessagesToolResponseAdapter` to customize plain-text formatting or message content, provided the emitted messages still follow Anthropic's `tool_result` schema. Alternatively, supply your own adapter instance when constructing the agent.

## Where it is used

* Automatically when you construct `AnthropicMessagesAdapter` without specifying a custom `tool_adapter`.
* Any agent that wants to reuse the same Anthropic formatting logic can import and instantiate it directly.

## Related references

* [Adapters Overview](./index): Understand LLMAdapters and ToolResponseAdapters
* [Anthropic Messages Adapter](./anthropic_messages_adapter): Understand the LLM integration that uses this adapter.