GeminiImageMCP has 2 tools with acceptable naming (verb_noun pattern) and basic descriptions. However, both tools lack comprehensive parameter descriptions, input validation guidance, and output schema documentation. Parameter descriptions are minimal (1-2 sentences) and don't explain formats, constraints, or error recovery paths. No error handling guidance is present. The base64 image encoding format is mentioned but not with sufficient constraint clarity. Output schemas are not documented, callers cannot know what fields are returned. Schema definitions are present but incomplete relative to production baselines. This server lands in the C-range (fair) due to significant gaps in description depth, output documentation, and error handling.

• Add output schema documentation for both tools. Example: 'Returns {"file_path": string, "format": string, "size_bytes": number, "width": number, "height": number}'. This enables downstream tool chaining.
• Expand parameter descriptions with explicit constraints. For 'prompt': 'Text description of the desired image (1 - 2048 characters). Supports English and major languages; results best in English. Avoid URLs and sensitive information.' For 'encoded_image': 'Base64-encoded image data with MIME type prefix (format: "data:image/[format];base64,[data]"). Supported formats: png, jpeg, jpg, gif, webp. Max size: 20 MB.'
• Document error scenarios and recovery guidance. Add to both tool descriptions: 'On error, returns error code and message. Common errors: INVALID_IMAGE_FORMAT (check base64 encoding and MIME type), RATE_LIMIT_EXCEEDED (wait 60s and retry), API_KEY_INVALID (verify GEMINI_API_KEY is set).'
• Add explicit state modification warnings to descriptions. Prefix both with: 'Generates and saves an image file to OUTPUT_IMAGE_PATH (destructive write operation; images are not reversible). Returns the file path. Subsequent calls with the same prompt may generate different images due to model stochasticity.'
• Document API key setup in server-level documentation or README, not in tool parameters. Ensure environment variable injection is enforced server-side and never exposed as a tool parameter.
• Add parameter examples in the format of enums or constraints, not prose. For transform_image_from_encoded, document that supported formats are limited (not arbitrary).

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry