MySQL MCP server has well-structured tool definitions with complete input schemas and descriptions for all 7 tools. Naming follows verb_noun convention (list_, describe_, fetch, update, delete, truncate, modify_bulk). Descriptions are clear and action-oriented (avg ~120 chars). However, output schemas are completely undocumented, LLMs cannot predict what fields to expect from tool responses. Error handling lacks recovery guidance and categorization. Security is strong (no credentials exposed, SQL injection prevention via sanitizeIdentifier), but missing permission gates and audit trail patterns. Tool composition is sound with clear single responsibilities, though some parameter relationships are underdocumented.

• Document output schemas for all tools. Example: 'list_tables returns {tables: [{name: string, rows: number, columns: number}]}'. Include field types and whether results are paginated.
• Enhance error messages with recovery guidance. Replace 'Invalid identifier' with 'Invalid table name "xyz". Only letters, numbers, underscores allowed. Call list_tables() to see available tables.'
• Add conditional parameter documentation to modify_bulk: 'group_by: required for deduplicate task only. column: required for normalize and cleanup tasks. from_value/to_value: required for normalize task only.'
• Implement permission gates and audit logging. Add scope declarations to tool descriptions (e.g., 'Requires write:database scope'). Log caller identity, timestamp, parameters, and outcome to stderr or external audit system.
• Clarify fetch pagination strategy. Document whether offset-based pagination is recommended for large result sets, and provide guidance on when to use limit/offset vs. iterative queries.