generate_image existed in the prompt sections, the executor and the image_gen
MCP server, but not in FUNCTION_TOOL_SCHEMAS. API models are only sent schemas
from that list, so the tool selector could pick it and the schema filter would
drop it again — the model then improvised text-shaped calls it had no way to
make work.
The existing JSON fallback in function_call_to_tool_block already produces
content the executor parses, so no converter branch is needed. A required-args
entry is, though: without it a prompt-less call falls through to the line
parser and the whole JSON blob becomes the image prompt.
Fixes#5520
Co-Authored-By: Claude <noreply@anthropic.com>
VykosMolt