Simon Willison’s Weblog

llm-anthropic 0.16. New release of my LLM plugin for Anthropic adding the new Claude 4 Opus and Sonnet models.

You can see pelicans on bicycles generated using the new plugin at the bottom of my live blog covering the release.

I also released llm-anthropic 0.16a1 which works with the latest LLM alpha and provides tool usage feature on top of the Claude models.

The new models can be accessed using both their official model ID and the aliases I've set for them in the plugin:

llm install -U llm-anthropic
llm keys set anthropic
# paste key here
llm -m anthropic/claude-sonnet-4-0 \
  'Generate an SVG of a pelican riding a bicycle'

This uses the full model ID - anthropic/claude-sonnet-4-0.

I've also setup aliases claude-4-sonnet and claude-4-opus. These are notably different from the official Anthropic names - I'm sticking with their previous naming scheme of claude-VERSION-VARIANT as seen with claude-3.7-sonnet.

Here's an example that uses the new alpha tool feature with the new Opus:

llm install llm-anthropic==0.16a1
llm --functions '                                                               
def multiply(a: int, b: int):
    return a * b
' '234324 * 2343243' --td -m claude-4-opus

Outputs:

I'll multiply those two numbers for you.
Tool call: multiply({'a': 234324, 'b': 2343243})
  549078072732
The result of 234,324 × 2,343,243 is **549,078,072,732**.

Here's the output of llm logs -c from that tool-enabled prompt response. More on tool calling in my recent workshop.