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

# Anthropic

> Trace Anthropic Python and Go SDK calls with OpenInference and send spans to Arize AX for LLM observability.

[Anthropic](https://www.anthropic.com/) provides the Claude family of large language models. Arize AX captures every Anthropic SDK call — prompts, responses, tool calls, and token usage — via the OpenInference instrumentors for [Python](https://github.com/Arize-ai/openinference/tree/main/python/instrumentation/openinference-instrumentation-anthropic) and [Go](https://github.com/Arize-ai/openinference/tree/main/go/openinference-instrumentation-anthropic-sdk-go), so you can debug, evaluate, and monitor Claude-powered applications.

## Prerequisites

* Python 3.10+ or Go 1.25+
* An Arize AX account ([sign up](https://arize.com/sign-up/))
* An `ANTHROPIC_API_KEY` from the [Anthropic Console](https://console.anthropic.com/)

## Launch Arize AX

1. Sign in to your [Arize AX account](https://app.arize.com/).
2. From **Space Settings**, copy your **Space ID** and **API Key**. You will set them as `ARIZE_SPACE_ID` and `ARIZE_API_KEY` below.

## Install

<CodeGroup>
  ```bash Python theme={null}
  pip install arize-otel openinference-instrumentation-anthropic anthropic
  ```

  ```bash Go theme={null}
  go get \
    github.com/Arize-ai/arize-otel-go \
    github.com/Arize-ai/openinference/go/openinference-instrumentation-anthropic-sdk-go \
    github.com/anthropics/anthropic-sdk-go
  ```
</CodeGroup>

## Configure credentials

```bash theme={null}
export ARIZE_SPACE_ID="<your-space-id>"
export ARIZE_API_KEY="<your-api-key>"
export ARIZE_PROJECT_NAME="anthropic-tracing-example"
export ANTHROPIC_API_KEY="<your-anthropic-api-key>"
```

## Setup tracing

<CodeGroup>
  ```python Python theme={null}
  # instrumentation.py
  import os

  from arize.otel import register
  from openinference.instrumentation.anthropic import AnthropicInstrumentor

  tracer_provider = register(
      space_id=os.environ["ARIZE_SPACE_ID"],
      api_key=os.environ["ARIZE_API_KEY"],
      project_name=os.environ["ARIZE_PROJECT_NAME"],
  )

  AnthropicInstrumentor().instrument(tracer_provider=tracer_provider)
  print("Arize AX tracing initialized for Anthropic.")
  ```

  ```go Go theme={null}
  // main.go
  //
  // Go integrations live in a single file — the tracer setup, the
  // instrumented middleware, and the messages call all sit inside main().
  // The `Run Anthropic` step below is just `go run main.go`.
  package main

  import (
      "context"
      "fmt"
      "log"
      "os"
      "time"

      arizeotel "github.com/Arize-ai/arize-otel-go"
      anthropicotel "github.com/Arize-ai/openinference/go/openinference-instrumentation-anthropic-sdk-go"
      "github.com/anthropics/anthropic-sdk-go"
      "github.com/anthropics/anthropic-sdk-go/option"
      "go.opentelemetry.io/otel"
  )

  func main() {
      ctx := context.Background()

      projectName := os.Getenv("ARIZE_PROJECT_NAME")
      if projectName == "" {
          projectName = "anthropic-tracing-example"
      }

      // Register reads ARIZE_SPACE_ID / ARIZE_API_KEY from the environment.
      tp, err := arizeotel.Register(ctx, arizeotel.Options{
          ProjectName: projectName,
      })
      if err != nil {
          log.Printf("register tracer: %v", err)
          return
      }
      defer func() {
          shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
          defer cancel()
          _ = tp.Shutdown(shutdownCtx)
      }()

      fmt.Println("Arize AX tracing initialized for Anthropic.")

      // The middleware wraps every /v1/messages request in an
      // LLM-kind span. The SDK reads ANTHROPIC_API_KEY from the environment.
      client := anthropic.NewClient(
          option.WithMiddleware(anthropicotel.Middleware(otel.Tracer(projectName))),
      )

      resp, err := client.Messages.New(ctx, anthropic.MessageNewParams{
          Model:     "claude-sonnet-4-5",
          MaxTokens: 256,
          Messages: []anthropic.MessageParam{
              anthropic.NewUserMessage(anthropic.NewTextBlock(
                  "Why is the ocean salty? Answer in two sentences.",
              )),
          },
      })
      if err != nil {
          log.Printf("anthropic: %v", err)
          return
      }

      for _, block := range resp.Content {
          fmt.Println(block.Text)
      }
  }
  ```
</CodeGroup>

<Note>
  **Go SDK** Only `/v1/messages` is instrumented today. Streaming responses pass through unchanged, but `output.value` and token counts are not populated for streaming spans yet. `tool_use` content blocks in messages are not yet captured as `message.tool_calls` attributes — wrap your tool execution in manual TOOL spans, see [Manual instrumentation](/ax/instrument/manual-instrumentation).
</Note>

## Run Anthropic

<CodeGroup>
  ```python Python theme={null}
  # example.py

  # Importing instrumentation first ensures tracing is set up
  # before `anthropic` is imported.
  from instrumentation import tracer_provider

  import anthropic

  # The client reads ANTHROPIC_API_KEY from the environment.
  client = anthropic.Anthropic()

  message = client.messages.create(
      model="claude-sonnet-4-5",
      max_tokens=256,
      messages=[
          {
              "role": "user",
              "content": "Why is the ocean salty? Answer in two sentences.",
          },
      ],
  )

  print(message.content[0].text)
  ```

  ```bash Go theme={null}
  # The full example lives in main.go above.
  go run main.go
  ```
</CodeGroup>

### Expected output

```text wrap theme={null}
Arize AX tracing initialized for Anthropic.
The ocean is salty because rivers continuously dissolve mineral salts from rocks and soil and carry them to the sea, where they accumulate over millions of years. Water leaves the ocean through evaporation but the salts remain, steadily concentrating until reaching today's roughly 3.5% salinity.
```

## Verify in Arize AX

1. Open your Arize AX space and select project **`anthropic-tracing-example`**.
2. You should see a new trace within \~30 seconds containing an LLM span — `messages.create` for the Python SDK or `anthropic.messages.create` for the Go SDK — with the prompt, response, and token usage attached.
3. If no traces appear, see [Troubleshooting](#troubleshooting).

## Troubleshooting

* **No traces in Arize AX.** Confirm `ARIZE_SPACE_ID` and `ARIZE_API_KEY` are set in the same shell that runs the example. Enable OpenTelemetry debug logs with `export OTEL_LOG_LEVEL=debug` and re-run.
* **Anthropic spans missing but other spans present (Python).** `AnthropicInstrumentor().instrument(...)` must run before any `import anthropic` in the application. Make sure `instrumentation.py` is the first import in your entry point.
* **`401` from Anthropic.** Verify `ANTHROPIC_API_KEY` is set and has access to the model in the example. Swap `claude-sonnet-4-5` for a model your key can call.
* **Go process exits before spans flush.** `arize-otel-go` uses a batched span processor by default. The `defer tp.Shutdown(...)` block in `main.go` is what flushes the batch — without it, short-lived programs lose their last spans. Pass `SimpleProcessor: true` to `arizeotel.Register` if you want synchronous export instead.

## Resources

<CardGroup>
  <Card icon="book-open" href="https://docs.anthropic.com/" title="Anthropic Documentation" horizontal />

  <Card icon="terminal" href="https://github.com/Arize-ai/openinference/tree/main/python/instrumentation/openinference-instrumentation-anthropic" title="OpenInference Anthropic Instrumentor (Python)" horizontal />

  <Card icon="github" href="https://github.com/Arize-ai/openinference/blob/main/python/instrumentation/openinference-instrumentation-anthropic/examples/messages_create.py" title="Anthropic Tracing Example (messages.create)" horizontal />

  <Card icon="github" href="https://github.com/Arize-ai/openinference/blob/main/python/instrumentation/openinference-instrumentation-anthropic/examples/multiple_tool_calling.py" title="Anthropic Tracing Example (tool calling)" horizontal />

  <Card icon="github" href="https://github.com/anthropics/anthropic-sdk-go" title="Anthropic Go SDK" horizontal />

  <Card icon="terminal" href="https://github.com/Arize-ai/openinference/tree/main/go/openinference-instrumentation-anthropic-sdk-go" title="OpenInference Anthropic Instrumentor (Go)" horizontal />
</CardGroup>