Documentation
LLM consumption
Providers
Anthropic

Anthropic

Configure Anthropic (Claude models) as an LLM provider in agentgateway.

Configuration

Review the following example configuration. 
binds:
- port: 3000
  listeners:
  - routes:
    - backends:
      - ai:
          name: anthropic
          provider:
            anthropic:
              model: claude-haiku-4-5-20251001
          routes:
            /v1/messages: messages
            /v1/chat/completions: completions
            /v1/models: passthrough
            "*": passthrough
      policies:
        backendAuth:
          key: "$ANTHROPIC_API_KEY"
Review the following example configuration.
Setting Description
name The name of the LLM provider for this AI backend, anthropic.
model Optionally set the model to use for requests. If set, any models in the request are overwritten. If not set, the request must include the model to use.
routes Include the routes to the LLM endpoints that you want to support. The keys are URL suffix matches, such as "/v1/messages" and "/v1/chat/completions". The special * wildcard matches any path. If not specified, all traffic is treated as OpenAI’s chat completions format. The messages format processes requests in Anthropic’s native messages format. This enables full compatibility with Claude Code and other Anthropic-native tools.
backendAuth Anthropic uses API keys for authentication. You can optionally configure a policy to attach an API key that authenticates to the LLM provider on outgoing requests. If you do not include an API key, each request must pass in a valid API key.

Example request

After running agentgateway with the configuration from the previous section, you can send a request to the v1/messages endpoint. Agentgateway automatically adds the x-api-key authorization and anthropic-version headers to the request. The request is forwarded to the Anthropic API and the response is returned to the client.

curl -X POST http://localhost:3000/v1/messages \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-3-5-haiku-20241022",
    "max_tokens": 100,
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

Example response:

{
  "model": "claude-haiku-4-5-20251001",
  "usage": {
    "input_tokens": 9,
    "output_tokens": 21,
    "cache_creation_input_tokens": 0,
    "cache_read_input_tokens": 0,
    "cache_creation": {
      "ephemeral_5m_input_tokens": 0,
      "ephemeral_1h_input_tokens": 0
    },
    "service_tier": "standard"
  },
  "content": [
    {
      "text": "Hi there! How are you doing today? Is there anything I can help you with?",
      "type": "text"
    }
  ],
  "id": "msg_01QdUEuzvXfjLh1HfMQd4UHP",
  "type": "message",
  "role": "assistant",
  "stop_reason": "end_turn",
  "stop_sequence": null
}

Connect to Claude Code

Connect to Claude Code locally to verify access to the Anthropic provider through agentgateway.

  1. Get your Anthropic API key from the Anthropic Console and save it as an environment variable.

    export ANTHROPIC_API_KEY="sk-ant-api03-your-actual-key-here"

  2. Start agentgateway with the following configuration. Make sure that the v1/messages route is set so that Claude Code can connect to agentgateway.

    cat > config.yaml << EOF
binds:
- port: 3000
  listeners:
  - routes:
    - backends:
      - ai:
          name: anthropic
          provider:
            anthropic:
              model: claude-haiku-4-5-20251001
          routes:
            /v1/messages: messages
            /v1/chat/completions: completions
            /v1/models: passthrough
            "*": passthrough
      policies:
        backendAuth:
          key: "$ANTHROPIC_API_KEY"
EOF

agentgateway -f config.yaml

  3. In another terminal, configure Claude Code to use the agentgateway instance that is running on your localhost.

    export ANTHROPIC_BASE_URL="http://localhost:3000"

  4. Start Claude Code with the new configuration.

    claude

  5. Send a test request through Claude Code, such as Hello.

  6. In the terminal where you run agentgateway, check the logs. You should see the requests in agentgateway logs. Claude Code continues to work normally while benefiting from any agentgateway features that you added, such as traffic management, security, and monitoring.

    Example output:

    2025-10-16T20:10:17.919575Z	info	request gateway=bind/3000 listener=listener0 route_rule=route0/default route=route0 endpoint=api.anthropic.com:443 src.addr=[::1]:59011 http.method=POST http.host=localhost http.path=/v1/messages?beta=true http.version=HTTP/1.1 http.status=200 gen_ai.operation.name=chat gen_ai.provider.name=anthropic gen_ai.request.model=claude-haiku-4-5-20251001 gen_ai.response.model=claude-haiku-4-5-20251001 gen_ai.usage.input_tokens=4734 gen_ai.usage.output_tokens=32 gen_ai.request.temperature=0 gen_ai.request.max_tokens=512 duration=1900ms
Multiple LLM providersAzure