Anthropic

Claude LLM provider for Voxray. Supports the full Claude 3 and Claude 4 model families as the LLM stage of the STT → LLM → TTS pipeline.

Capabilities

STT

Not supported

LLM

Full Claude model family via the Messages API

TTS

Not supported

Realtime

Not supported

Anthropic currently provides LLM capability only. Pair it with a supported STT provider (e.g. "groq" or "openai") and TTS provider (e.g. "elevenlabs" or "openai") to build a complete voice pipeline.

API Key

Set ANTHROPIC_API_KEY as an environment variable or pass it inline under api_keys in config.json.

Get your key at console.anthropic.com.

Quick Config

config.json

{
  "stt_provider": "groq",
  "llm_provider": "anthropic",
  "tts_provider": "elevenlabs",
  "model": "claude-haiku-4-5-20251001",
  "api_keys": {
    "anthropic": "sk-ant-...",
    "groq": "gsk_...",
    "elevenlabs": "..."
  }
}

Environment variable

export ANTHROPIC_API_KEY="sk-ant-..."
export GROQ_API_KEY="gsk_..."
export ELEVENLABS_API_KEY="..."

Then in config.json:

{
  "stt_provider": "groq",
  "llm_provider": "anthropic",
  "tts_provider": "elevenlabs",
  "model": "claude-haiku-4-5-20251001"
}

Available Models

Model	Speed	Cost	Best For
claude-haiku-4-5-20251001	Fastest	Lowest	High-throughput voice agents, short-answer tasks, latency-sensitive workflows
claude-sonnet-4-6	Balanced	Medium	General-purpose voice agents, customer support, nuanced reasoning
claude-opus-4-6	Slowest	Highest	Complex multi-step reasoning, analysis tasks where accuracy outweighs latency

The default model when model is empty is claude-3-sonnet-20240229 (defined as DefaultLLMModel in pkg/services/anthropic/llm.go).

API Details

Property	Value
Endpoint	https://api.anthropic.com/v1/messages
Version header	anthropic-version: 2023-06-01
Auth header	x-api-key: <your-key>
Timeout	60 seconds per request
Max tokens	1024 per response (hardcoded default)
Transport	Shared http.Transport with 10 idle connections per host, 90 s idle timeout

Configuration Reference

Key	Type	Description
llm_provider	string	Set to "anthropic"
model	string	Claude model ID (e.g. "claude-haiku-4-5-20251001"); defaults to "claude-3-sonnet-20240229"
api_keys.anthropic	string	Anthropic API key (falls back to ANTHROPIC_API_KEY)
stt_provider	string	Required — Anthropic does not provide STT; use "groq", "openai", etc.
tts_provider	string	Required — Anthropic does not provide TTS; use "elevenlabs", "openai", etc.

Latency Consideration

The Anthropic provider returns full responses, not streaming tokens. The implementation sets "stream": false in the API request and delivers the complete text as a single LLMTextFrame when the response arrives. This means TTS does not receive text incrementally — the first audio chunk has materially higher latency than streaming providers like OpenAI or Groq.

To mitigate this:

• Use shorter system prompts.
• Prefer claude-haiku-4-5-20251001 over larger models for faster time-to-first-token.
• Consider sentence-level TTS batching if your pipeline supports it.
• For latency-critical agents, evaluate "llm_provider": "groq" or "llm_provider": "openai", both of which stream tokens as they are produced.

Tool Calling

The Anthropic provider does not implement LLMServiceWithTools. MCP tool integration is not available with this provider. To use MCP tools, switch llm_provider to "openai" (the other provider that implements the tools interface).

Notes and Limitations

• System messages in the conversation are concatenated and sent as the top-level system field in the Anthropic request; they are not included in the messages array.
• Messages with empty content are silently dropped before the request is sent.
• The max_tokens limit is hardcoded to 1024. Very long model outputs will be truncated. If your use case requires longer responses, this requires a code-level change in pkg/services/anthropic/llm.go.
• Only "user" and "assistant" roles are forwarded to Anthropic. Any message with a role other than "system" or "assistant" is treated as a user message.