Anthropic Python SDK v1.0 breaks httpx and drops the Completions API
The jump to httpx2 lifts the Python floor to 3.10 and pulls temperature from the signature, as llm 0.27 and a Codex MCP change ripple through the toolchain.
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The httpx2 swap under every request
v1.0 replaces httpx with httpx2, a maintained fork now stewarded by Pydantic Services. Custom-client code needs `import httpx2 as httpx`, and anything that patches httpx (respx, pytest-httpx, OpenTelemetry) has to call `httpx2.alias_httpx()` at startup or lose its instrumentation.
The Completions API and Python 3.9 are gone
`client.completions.create()` and the `HUMAN_PROMPT` / `AI_PROMPT` constants are removed — move any legacy calls to `messages.create()`. The minimum Python is now 3.10; if you are stuck on 3.9, pin `anthropic==0.125.0`, the last v0.x release.
temperature left the method signature
`temperature`, `top_p`, and `top_k` are out of the typed `messages.create/stream/parse` signatures. They still pass through `extra_body`, but seven current Claude models reject any non-default value regardless. `AnthropicBedrock` now raises if no region is set instead of silently defaulting to us-east-1.
The ecosystem is racing to catch up
Simon Willison shipped llm-anthropic 0.27 on Aug 24 for v1.0 compatibility, using Fable 5 to automate the migration. Expect a wave of pinned deps and patch releases across every library that wraps the Anthropic client this week.
OpenAI retires the codex mcp-server command
A same-week shift from the other side of the toolchain: OpenAI deprecated the `codex mcp-server` command on Aug 24 in favor of the Codex app server. If you wired Codex into an MCP client, the launch command needs updating.