Anthropic¶

The Messages API over raw httpx2. Registered as anthropic, with the alias claude.

streaming structured output (emulated) tool calls health discovery

Setup¶

client = ai.Client(
    [
        ai.ProviderSettings.of("anthropic", api_key="env://ANTHROPIC_API_KEY"),
    ]
)
result = client.generate(prompt, target="anthropic:claude-sonnet-4-5")

No extra required.

Supported¶

Behavior	Support
Streaming	Native, typed SSE events
Structured output	Emulated as a forced tool call
Tools	Native
Reasoning	Extended thinking, budgeted in tokens
Usage	Input, output, plus cache read/write
Cost	Cataloged pricing

Reasoning¶

Since Anthropic budgets thinking in tokens rather than naming levels, reasoning effort maps to a budget:

Effort	Wire form
`minimal`	`{"type": "disabled"}`
`low`	1024 tokens
`medium`	4096 tokens
`high`	16384 tokens

Thinking arrives as ReasoningDelta events on the event stream. Thinking starts the first-token clock (the model is working and the user sees activity), but its text is excluded from the answer.

Structured Output¶

Anthropic has no response_format field, so a schema becomes a single forced tool call, which the API does constrain. The caller still gets a normal validated result.structured; the emulation is invisible except in structured_mechanism. See structured output for how mechanisms are chosen.

Pointing This Adapter Elsewhere¶

Several other services expose an Anthropic-Messages-shaped endpoint. This adapter serves any of them through a base_url override; nothing else changes:

ai.ProviderSettings.of(
    "anthropic",
    base_url="https://api.deepseek.com/anthropic",
    api_key="env://DEEPSEEK_API_KEY",
)

DeepSeek, xAI, and several of the presets document such endpoints. Prefer the provider's own adapter or preset unless Messages-dialect behavior is specifically needed, since provider-specific features are wired only there.

Multimodal Inputs¶

Images and PDF documents accept inline bytes or provider-fetchable URLs. The adapter emits native image/document content blocks. Audio input is not part of this Messages projection and fails explicitly. See multimodal inputs for the normalized input model.

Notes¶

System messages become the top-level system field.
max_tokens is required by the API; AnyInfer sends 4096 when none is set rather than letting the request fail with a 400.
Tool results ride on a user turn in this dialect, not a tool role.
Model listing is cursor-paginated, and pagination is followed automatically.

Wire Contract¶

For the exact request/response fields this adapter depends on, see contracts/anthropic.md.