The backend MCP tools `send_direct_message_as_user` and
`send_message_as_user` both require `title` as a required field.
However, the skill documentation and --help Long text described
--title as "optional", causing AI models to omit it and trigger
a vague `business error: success=false`.
Update descriptions in:
- skills/references/products/chat.md
- internal/helpers/chat.go (command Long text)
Closes#173
修雨
b101d5b12b