Anthropic provider

Setup

You need an API key from console.anthropic.com.

1. Settings → Providers → + Add provider → Anthropic.
2. Paste your API key into the API key field.
3. Click Test connection. Cerevisor asks Anthropic for your model list to confirm the key works.
4. Click Save.

The key is stored in your OS keychain. It never lives in plain text on disk or in any .cerevisor file.

Models

Cerevisor asks Anthropic which models your account can use and shows them everywhere a model picker appears. The most-used Claude models you'll see:

Model	Best for	Notes
Claude Opus 5	Highest quality, deepest reasoning, long autonomous runs.	What the Opus shortcut in the model picker picks. Same price as Opus 4.8, so nothing gets more expensive by switching. Earlier Opus 4.x models stay available if you type their id.
Claude Sonnet 5	Balanced — strong quality at lower cost.	What the Sonnet shortcut picks; the default for most workloads.
Claude Haiku 4.5	Fastest, cheapest.	Great for reviewers, classifiers, simple transforms.

The frontier-tier Claude Fable 5 is also available when your account has access to it; it costs more per token than Opus 5, so reserve it for the work that needs it. For models that support reasoning, the model picker shows a Thinking control (Off → Ultra) that sets how much the model may think before answering.

Cost

Cerevisor works out cost from the usage Anthropic reports for each response and the model's price. The status bar shows running cost during a run; the audit log saves the breakdown.

Prices change as Anthropic releases new models. Press Refresh models to bring in new models and their prices without waiting for a Cerevisor update. Until Cerevisor has a price for a new Anthropic model, it counts it at Anthropic's most expensive rate, so your spending limits still apply. See Keeping your models current.

Default model

In the Library entry, you can set a default model for this provider. An agent whose model is set to Auto uses this default.

Caching, tools and images

Automatic retries, prompt caching, tool use, and image inputs all work without setup.

Prompt caching is enabled by default when the API and the model support it; this can substantially reduce cost for workflows with shared context (e.g. multi-agent workflows reading the same project folder).

Common errors

Error	What it means	Fix
401 Unauthorized	Invalid API key.	Re-check the key. Generate a new one in the Anthropic console if needed.
429 Rate limited	You hit your account's rate limit.	Wait and retry, or upgrade your Anthropic plan.
Network error	Anthropic is unreachable.	Check your network. Cerevisor retries automatically with backoff.