Anthropic

Provider value: anthropic (default)

Anthropic is the default provider. If no --provider flag is set, ra uses Anthropic.

Setup

export RA_ANTHROPIC_API_KEY=sk-ant-...
ra "Hello"

Environment variables

Variable	Required	Description
RA_ANTHROPIC_API_KEY	Yes	Anthropic API key
RA_ANTHROPIC_BASE_URL	No	Custom base URL (for proxies or compatible APIs)

Models

Model	Notes
claude-sonnet-4-6	Default. Best balance of speed and capability
claude-opus-4-6	Most capable
claude-haiku-4-5-20251001	Fastest, cheapest. Used as default compaction model

ra --model claude-opus-4-6 "Design a distributed system"
ra --model claude-haiku-4-5-20251001 "Quick summary of this file" --file data.csv

Extended thinking

Enable extended thinking for deeper reasoning. Supported levels: low, medium, high.

ra --thinking high "Design a distributed cache"
ra --thinking medium "Review this architecture"

Or in config:

provider: anthropic
thinking: medium

Prompt caching

ra automatically applies cache hints to system prompts and tool definitions when using Anthropic. This reduces costs on multi-turn sessions without any configuration needed. Cached tokens are billed at a reduced rate — especially beneficial for sessions with large system prompts or many tools.

Custom base URL

Point ra at an Anthropic-compatible API proxy:

export RA_ANTHROPIC_BASE_URL=https://my-proxy.example.com/v1
ra "Hello"

Or via CLI flag:

ra --anthropic-base-url https://my-proxy.example.com/v1 "Hello"

See also

• Providers overview — switching between providers
• Context Control — extended thinking and prompt caching details
• Configuration — provider credentials reference