1.0-1

Return a tool result once, without a structured copy

Every tool result carried its value twice: as the JSON text of its one
content item and again as structuredContent. No tool declares an output
schema, so the protocol asks for no structured copy, and a client that
shows both made the model read every scene twice. The router now returns
only the text item and the error flag.

The MCP, model loop and worker host tests read the value from the content
text and check that no structured copy is sent.