MCP-Crawl4AI demonstrates solid definition quality with clear naming patterns, comprehensive parameter descriptions, and well-structured schemas. All 7 tools follow verb_noun naming conventions (scrape, crawl, create_session, etc.). Input parameters are consistently documented with descriptions and constraints. However, there are notable gaps in output schema documentation, error handling guidance, and some parameter details are incomplete. The tool set is well-composed for web crawling workflows, but lacks explicit error recovery patterns and output field specifications.

• Document the return type schema for every tool. For scrape/crawl, specify: {content: string, metadata: {title?: string, url: string, status_code: integer}, ...}. For create_session, return {session_id: string, expires_at: ISO8601, artifact_url?: string}. This enables LLM tool chaining.
• Add explicit error handling guidance to tool descriptions. E.g., scrape: 'May timeout if page is complex (timeout_ms exceeded) or CSS selector not found (invalid extraction_targets). Retry with increased timeout_ms or simpler selectors.' Include retryable vs fatal distinctions.
• Expand session lifecycle documentation. Clarify: create_session reserves browser state for multiple related crawls; close_session frees resources. Explain when artifacts are created (automatic capture during crawl?) vs retrieved (list_artifacts). Add example: 'Create a session, crawl multiple URLs with depth=1, list artifacts, then retrieve specific captured PDFs.'
• Add schema validation for extraction_targets. Define items as {type: 'css'|'xpath', selector: string, attribute?: string, ...} or reference crawl4ai's schema directly. Include brief example in description: 'e.g. [{"type": "css", "selector": ".article"}, ...]'.
• Document result limits and truncation behavior. For crawl: 'max_pages defaults to 50; results are truncated if exceeds MAX_RESPONSE_CHARS (25000). Remaining URLs are listed in truncated_urls field.' For list_artifacts: 'Returns up to 200 artifacts; use pagination tokens if available.'
• Add composition guidance in tool descriptions. Scrape should say: 'Use for single pages or simple extraction. For multi-page content or following links, use crawl instead.' crawl should say: 'Set depth=0 for single page, depth=1 to follow immediate links. Use crawl_many for parallel multi-URL operations.'