Anthropic Provider

The Anthropic provider uses the Messages API.

Configuration

Minimal Setup

export AGSH_PROVIDER=anthropic
export AGSH_MODEL=claude-sonnet-4-20250514
export ANTHROPIC_API_KEY=sk-ant-...
agsh

Config File

[provider]
name = "anthropic"
model = "claude-sonnet-4-20250514"

Supported Models

Any model available through the Anthropic Messages API:

• claude-opus-4-20250514
• claude-sonnet-4-20250514
• claude-haiku-4-5-20251001

Custom Base URL

To use an Anthropic-compatible proxy or gateway:

agsh --provider anthropic --model claude-sonnet-4-20250514 --base-url https://my-proxy.example.com

API Details

Endpoint: POST {base_url}/v1/messages

Headers:

• x-api-key: <api_key>
• anthropic-version: 2023-06-01
• content-type: application/json

System prompt: Sent as a top-level system field in the request body (not as a message).

Tool format: Tools are defined with input_schema instead of parameters:

{
  "name": "read_file",
  "description": "Read the contents of a file at the given path.",
  "input_schema": { "type": "object", "properties": { ... } }
}

Tool use and results: Expressed as content blocks within messages:

• Tool use: {"type": "tool_use", "id": "...", "name": "...", "input": {...}}
• Tool result: {"type": "tool_result", "tool_use_id": "...", "content": "..."}

Streaming: Uses Server-Sent Events with named event types: