This MCP server exposes 2 image generation tools with significant quality gaps. Both tools have reasonable descriptions (120-150 chars, within the 10-1024 baseline), but parameter schemas lack essential documentation and type precision. Input schemas ARE visible in the code, but many parameters have incomplete descriptions or ambiguous types. The generate_cover tool accepts a 'style' enum but doesn't document valid values in the parameter description itself, only in the tool description. The screenshot_html tool's integer parameters (width, height) lack min/max constraints. Neither tool has documented output schemas (what fields/metadata the PNG files contain, or what the function returns beyond 'a PNG'). Error handling is absent: no guidance on what happens if fonts are missing, if the output path is invalid, if HTML rendering fails, or how to recover. The server lacks any indication of how an LLM should know whether to use generate_cover vs screenshot_html, the distinction is unclear without domain expertise. Both tools perform file I/O (WRITE risk), but there's no mention of path validation or injection guards. Naming is acceptable (verb_noun format: generate_cover, screenshot_html), but descriptions could be more LLM-optimized (e.g., stating WHEN to use each tool and what the input/output relationship is).

• Add explicit enum constraints to 'style' and 'scheme' parameters. Instead of relying on tool description, define in parameter description: 'style must be one of: gradient, minimal, list, bold'.
• Document integer bounds: width 800-2000 (or actual range), height 1000-3000, etc. Prevent absurd values like width=1000000.
• Add output schema to both tools: specify that the tool returns a structured object with fields like {success: bool, file_path: string, width: int, height: int, error?: string} rather than bare PNG bytes.
• Add error handling guidance to descriptions. E.g., 'If the font is missing on macOS, the tool falls back to system default. If output_path is invalid or disk is full, an error message will indicate the issue.'
• Validate and sanitize path parameters. Reject paths containing '..', leading '/', or other traversal patterns. Document this in the parameter description.
• Clarify tool selection: add a 'When to use' section to each description. 'Use generate_cover when you have text and want to create a cover from scratch with predefined styles. Use screenshot_html when you already have an HTML template and need to render it to PNG.'
• Add parameter dependencies: document that 'items' only applies when style='list', and other styles ignore it (or reject it).
• Consider adding a 'preview' or 'dry_run' mode parameter to avoid destructive file writes without user confirmation (pattern: confirmation-request).