Single tool 'layout_check' with well-structured Zod schema, comprehensive parameter definitions, and detailed descriptions. Tool exhibits excellent naming (verb_noun pattern: 'layout_check'), extensive parameter documentation with constraints, and structured output design. However, output schema is not formally documented in the source code, only mentioned in the description text. Error handling provides actionable guidance. Schema validation is thorough with min/max bounds on numeric parameters and enum constraints on check types. Description is LLM-optimized and detailed (470+ chars), exceeding baseline. One critical gap: tool accepts 'url' parameter without documented network restrictions beyond a boolean flag, and the description implies localhost-only restriction but the implementation allows arbitrary URLs if allowNetwork=true, a security concern that should be more explicitly gated.

• Add a formal JSON Schema definition for the tool's return type in the source code (e.g., as a Zod schema or TypeScript interface exported alongside InputSchema). Document the structure of the 'report' object returned in structuredContent.
• Implement explicit localhost validation for the 'url' parameter when allowNetwork is false. Return a clear error message: 'Network requests disabled. URL must be localhost, file://, or use allowNetwork=true.' This prevents silent failures and guides agent recovery.
• Document parameter interdependencies explicitly. Update the 'minOverlapPx' and 'minOverlapArea' descriptions to state: 'Only applies to overlap-based checks (text-overlap, element-collision, container-overflow). Ignored if those checks are not in the checks array.'
• Validate executablePath: restrict it to a configured allowlist of known safe paths or require explicit environment variable opt-in (e.g., LAYOUT_DOCTOR_CHROMIUM). Document this constraint in the parameter description.
• Expand error messages returned by errorResult() to include recovery hints. For example, if 'html | path | url' validation fails, suggest which parameter to use based on the agent's intent: 'For live websites, use url. For files, use path. For generated HTML, use html.'
• Add per-check documentation. Each check type (placeholder-left, draft-text-left, etc.) should have a one-line description in the checks parameter annotation, e.g., '["placeholder-left", // detects unresolved placeholder text like {{name}}]'.