Claude (Anthropic)

Claude is a first-class provider: a bare claude-* model name routes to the real Messages API (/v1/messages, not a translation layer), authenticated by an API key or a Claude subscription login. Gateways — Bedrock Access Gateway, Azure Foundry, LiteLLM — work on any /anthropic/v1 path.

Get an API key

1. Sign in at console.anthropic.com
2. Open Settings → API Keys
3. Click 'Create Key' and name it
4. Copy the sk-ant- key (shown once)
5. Add credits under Settings → Billing

Create a key ↗ · Pricing ↗

No ongoing free tier; buy prepaid credits (a small trial credit may apply).

Or use your Claude subscription

If you already pay for Claude, you don't need an API key. Paste the OAuth token from your Claude login (sk-ant-oat…) into /enable anthropic — mantis recognises the shape, stores it as ANTHROPIC_AUTH_TOKEN, sends it as Authorization: Bearer with the Claude Code identity Anthropic expects, and Opus, Sonnet and Haiku all answer on your subscription's usage window. The dashboard and the terminal footer show the source as OAuth token.

Enable

export ANTHROPIC_API_KEY=sk-ant-...        # shell profile — survives forever
# or, for a subscription / gateway token:
export ANTHROPIC_AUTH_TOKEN=sk-ant-oat...

or in the terminal — detects key vs. token by shape and validates before saving:

/enable anthropic

or pick any locked 🔒 Claude (Anthropic) model in /models and paste either credential inline.

Models

Starter menu (once enabled, /models fetches the provider's full live list):

• claude-opus-5
• claude-sonnet-5
• claude-haiku-4-5
• claude-fable-5-1

Switch anytime — /model claude jumps to the flagship, /model opus / /model sonnet / /model haiku resolve a tier; context carries over.

SDK

No backend needed — the name selects the native adapter:

from mantis_agent import MantisAgentOptions
options = MantisAgentOptions(model="claude-opus-5")     # $ANTHROPIC_API_KEY or $ANTHROPIC_AUTH_TOKEN

The explicit forms say the same thing, or point the adapter at a gateway:

from mantis_agent import MantisAgentOptions
direct = MantisAgentOptions(model="claude-opus-5", backend="anthropic")
gateway = MantisAgentOptions(model="claude-opus-5", backend="https://gateway.example/anthropic/v1")

Notes

• Thinking follows the model generation. The universal thinking config becomes budget_tokens on Haiku 4.5 and older, adaptive plus output_config.effort on Opus 4.7+/5 and Sonnet 5 (they reject budget_tokens), and effort only on Fable. An unknown id is retried once with the other form, and temperature is dropped where sampling was removed.
• Prompt caching is on by default, with the cache breakpoint on the last block so the whole prefix is reused.
• Tool definitions are converted to Anthropic's input_schema shape automatically; structured output (response_model / response_format) uses the native envelope.
• Bedrock and Vertex credentials are understood too — paste an AWS key or a GCP token and the request is signed for the regional host.
• A 429 with an OAuth token is a spent usage window on your subscription, not a missing entitlement; wait it out or switch to an API key.