Single tool 'generate_image' has a well-structured schema and comprehensive description, but lacks critical error guidance patterns and security best practices. The tool definition is explicit and visible in src/index.ts with proper JSON Schema input validation via Zod. Description is detailed (194 chars), exceeding the 10-char minimum and within the 10-1024 baseline range. However, the tool accepts an API key as a parameter (google_api_key), violating secret-injection patterns. No error handling guidance is provided to the LLM about recovery paths (e.g., 'if blocked, try a different prompt'). The schema itself is well-typed with proper descriptions for each parameter, including optional flags and defaults. Output is returned as structured ToolContent[] with inline images and summary text.

• Remove google_api_key parameter entirely. Move API key resolution to server-side environment variable only (already falls back to GOOGLE_API_KEY env var in resolveApiKey function). Document this in tool description: 'Ensure GOOGLE_API_KEY environment variable is set.'
• Enhance tool description with error recovery guidance: 'If generation is blocked due to content policy, try rephrasing the prompt or providing different reference images. For quota errors, wait and retry.'
• Add per-image success/failure structure to output when saving multiple images, in case some fail during write.
• Document generation parameters (temperature: 0.95, topP: 0.9) in the tool description so the LLM understands output variability and can coach users on consistency expectations.
• Declare supported MIME types and file size limits for reference_images in the description, e.g., 'Supported formats: JPEG, PNG, WebP, GIF. Each image should be under 20MB.'
• Return IDs or identifiers (file paths or checksums) for generated images to enable idempotency tracking and audit trails.
• Consider adding an optional 'seed' parameter for reproducibility, documented as 'If set, generation will be deterministic; omit for varied results.'
• Log tool invocations (prompt, reference image count, output directory) for audit and debugging, without logging the API key.