Two tools with basic schemas and descriptions, but significant gaps in parameter documentation, error handling guidance, and output schema clarity. generate_image has 6 parameters but only 2 have descriptions in the visible code. login lacks parameter descriptions entirely. Neither tool documents return structure or error recovery paths. Descriptions are present but generic (194-char baseline suggests room for improvement). No evidence of input validation, error categorization, or recovery guidance.

• Add explicit parameter descriptions to both tools. For generate_image: document that 'model' accepts 'Fast|Thinking|Pro', 'tool' is a Gemini tool override, 'headless' controls browser visibility, 'debug' pauses at inspection points. For login: document that 'force' (default false) re-authenticates even if session exists.
• Document return schemas as JSON objects. generate_image returns {ok: bool, prompt: str, model: str, tool: str, output_dir: str, files: [str], image_count: int, used_saved_session: bool|null, message: str, error_code: str}. login returns {ok: bool, session_path: str, message: str}.
• Add error recovery hints. For AuthRequiredError, return 'Auth required. Call login() first to save a session.' For validation errors, return 'Prompt is required and must be non-empty.'
• Declare enums for constrained parameters. model: enum ['Fast', 'Thinking', 'Pro']. tool: enum of valid Gemini tools (if known). headless, debug, force: boolean with clear defaults.
• Add input validation with actionable error messages. Validate prompt is non-empty and under reasonable length. Validate output_dir is writable. Return specific error codes (VALIDATION_ERROR, AUTH_REQUIRED, IO_ERROR) so agents can categorize and retry intelligently.