VIMO server has 9 tools with reasonable naming conventions (verb_noun pattern) and bilingual descriptions. However, critical gaps in parameter descriptions, output schema documentation, and error handling significantly limit production readiness. Most tools lack explicit output schema definitions, agent developers cannot predict what fields to expect. Parameter descriptions are sparse or missing entirely. Error handling is absent, no guidance for timeouts, rate limits, or invalid inputs. The server enforces API key validation early (good security posture) and applies basic input sanitization, but the MCP tool definitions themselves fall short of the 'A' standard. Average per-tool score: 58/100.

• Add explicit output schema documentation for each tool. Example: 'Returns: {symbol: string, price: number, change_pct: number, volume: number}'. This must appear in the tool description or as a separate outputSchema field in MCP 2025+.
• Convert 'sector', 'index', 'strategy', and 'category' parameters to enum constraints. Example: sector: {type: 'string', enum: ['VN30', 'Banking', 'Tech', 'Energy', 'Retail'], description: 'Stock sector filter'}.
• Expand get_technical_signals description to ~150 characters explaining what signals are returned and when to use it (e.g., 'Returns buy/sell strength for day-trading confirmation. Call after price_history to validate short-term trends.').
• Add parameter descriptions for 'days' (e.g., 'Number of trading days (1-365; default 30)') and 'limit' (e.g., 'Max search results returned (1-50; default 10)').
• Document all possible errors and recovery paths in tool descriptions. Example: 'On timeout (>30s), retry with a smaller date range. On 429 (rate limit), wait 60s and retry. On 401, verify VIMO_API_KEY.'
• Implement per-tool result limits in descriptions. Example: 'Returns up to 50 results. Use offset/limit to paginate.' Add total_count and next_cursor to responses.
• Add field mappings to help agents chain tools. Example, search_stocks returns 'symbol', ensure get_stock_info accepts 'symbol' parameter (currently correct, but verify all tools for consistency).
• Consider splitting screen_stocks into screen_stocks_buffett, screen_stocks_graham, etc. to avoid parameter ambiguity, or add enum with all 13 strategy names.