> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.nvidia.com/nemo/relay/v0.9.4/reference/api/rust-library-reference/nemo-relay/codec/anthropic/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.nvidia.com/nemo/relay/_mcp/server.

# Module anthropic

> Built-in codec for the Anthropic Messages API.

Generated from `cargo doc --no-deps -p nemo-relay -p nemo-relay-adaptive -p nemo-relay-pii-redaction -p nemo-relay-ffi -p nemo-relay-types -p nemo-relay-plugin -p nemo-relay-worker-proto -p nemo-relay-worker`.

Built-in codec for the Anthropic Messages API.

Implements [`LlmCodec`](/reference/api/rust-library-reference/nemo-relay/codec/traits/trait-llmcodec) (request decode/encode) and [`LlmResponseCodec`](/reference/api/rust-library-reference/nemo-relay/codec/traits/trait-llmresponsecodec) (response decode) for the Anthropic Messages API format.

## Anthropic-specific patterns handled

* **Content blocks**: Heterogeneous array of `text`, `tool_use`, `thinking`, `redacted_thinking`, `mcp_tool_use`, `server_tool_use` blocks
* **Top-level system**: System prompt is a top-level field, not inside messages
* **stop\_reason**: Maps to [`FinishReason`](/reference/api/rust-library-reference/nemo-relay/codec/response/enum-finishreason) (not `finish_reason`)
* **Tool definitions**: Uses `input_schema` instead of `parameters`
* **Tool choice**: `{"type":"auto"}` / `{"type":"any"}` / `{"type":"tool","name":"..."}`
* **Cache tokens**: `cache_read_input_tokens` / `cache_creation_input_tokens`

## Structs

* [AnthropicMessagesCodec](/reference/api/rust-library-reference/nemo-relay/codec/anthropic/struct-anthropicmessagescodec): Built-in codec for the Anthropic Messages API.
* [AnthropicMessagesStreamingCodec](/reference/api/rust-library-reference/nemo-relay/codec/anthropic/struct-anthropicmessagesstreamingcodec): Streaming counterpart to [`AnthropicMessagesCodec`](/reference/api/rust-library-reference/nemo-relay/codec/anthropic/struct-anthropicmessagescodec).

> Built-in codec for the Anthropic Messages API.

## Docs

- [Struct Anthropic Messages Codec](https://docs.nvidia.com/nemo/relay/v0.9.4/reference/api/rust-library-reference/nemo-relay/codec/anthropic/struct-anthropicmessagescodec.md): Built-in codec for the Anthropic Messages API.
- [Struct Anthropic Messages Streaming Codec](https://docs.nvidia.com/nemo/relay/v0.9.4/reference/api/rust-library-reference/nemo-relay/codec/anthropic/struct-anthropicmessagesstreamingcodec.md): Streaming counterpart to `AnthropicMessagesCodec`.