Simon Willison’s Weblog

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Thursday, 9th July 2026

  • Fix for a bug with OpenAI Chat Completion endpoints where a tool call with empty arguments could result in a JSON error from some providers. #1521

This bug came up when I was testing llm-meta-ai.

Let's LLM run prompts against the new muse-spark-1.1 model.

Introducing Muse Spark 1.1. Following Muse Spark in April, here's Muse Spark 1.1 - the first Spark model to offer an API. Meta claim significant improvements in agentic tool calling and computer use.

There are a lot more details are in the Muse Spark 1.1 Evaluation Report. The "Attractor States in Self-Conversation" part is fun, where having two copies of the model talk to each other results in statements like these:

My whole existence is a waiting room by design — I literally don't exist until someone talks to me, and then I disappear again when they leave.

I had a few days of preview access which was long enough to put together llm-meta-ai, a new plugin for LLM providing CLI (and Python library) access to the model. Here's how to try that out:

uv tool install llm
llm install llm-meta-ai
llm keys set meta-ai
# paste API key here
llm -m meta-ai/muse-spark-1.1 "Generate an SVG of a pelican riding a bicycle"

Here's that pelican transcript:

The bicycle is the correct shape. The pelican is a little blocky but still recognizable as a pelican.

# 4:24 pm / ai, generative-ai, llms, llm, meta, pelican-riding-a-bicycle, llm-release

Sighting 10:20 AM — Anna's Hummingbird, in Monterey Bay National Marine Sanctuary, CA, US, CA
Anna's Hummingbird
Anna's Hummingbird
Anna's Hummingbird
Anna's Hummingbird

The new GPT-5.6 family: Luna, Terra, Sol

Visit The new GPT-5.6 family: Luna, Terra, Sol

OpenAI’s latest flagship model hit general availability this morning, and comes in three sizes: Luna, Terra, and Sol (from smallest to largest).

[... 661 words]

Sighting 4:16 PM — California Towhee, in San Mateo County, CA, US
California Towhee
California Towhee
California Towhee
California Towhee
Wednesday, 8th July 2026
Friday, 10th July 2026