Summary

When the built-in autovisualiser extension is enabled, OpenAI-compatible runs fail before normal generation with:

Invalid schema for function 'autovisualiser__render_donut'

Environment

• Goose: 1.28.0
• macOS (Apple Silicon)
• Provider: openai
• Model: gpt-4o-mini

Minimal reproduction

OPENAI_HOST=https://api.openai.com \
OPENAI_BASE_PATH=/v1/chat/completions \
GOOSE_MODE=agent \
goose run \
  --provider openai \
  --model gpt-4o-mini \
  --no-profile \
  --with-builtin autovisualiser \
  --no-session \
  --quiet \
  --output-format json \
  --max-turns 4 \
  --text "Reply with exactly OK"

Actual result

400 Bad Request from provider layer:

Invalid schema for function 'autovisualiser__render_donut'. Please ensure it is a valid JSON Schema.

Expected result

The model should return OK (or at least continue without schema rejection).

Workaround

Disable autovisualiser in config (enabled: false) and rerun. The request succeeds.

Suspected area

render_donut schema in:

• crates/goose-mcp/src/autovisualiser/mod.rs

Possible culprit is the DonutChartData / DonutDataItem untagged enum schema shape for OpenAI-compatible function schema validation.