Two tools with clear, concise descriptions (avg 115 chars, within baseline 34-392). Both have proper JSON Schema with type definitions. However, parameter descriptions are minimal or absent: sql_query lacks guidance on format/constraints; describe_schema has no parameters. No output schema documentation. Error handling returns isError=true with text, but lacks recovery guidance or categorization. Tool names follow verb_noun pattern (sql_query, describe_schema) and are appropriately specific for a guardrail server. Composition is sound, each tool has one responsibility. Missing: parameter validation rules in descriptions, output schema docs, error classification, and idempotent/readonly hints.

• Add parameter description to sql_query.sql: 'A single SELECT or WITH...SELECT statement. Max 10,000 chars. Forbidden: PRAGMA, INSERT, UPDATE, DELETE, DROP, ALTER. Example: SELECT id, name FROM customers WHERE country = ?'
• Document output schemas in tool descriptions. E.g., 'Returns: {content: [{type: "text", text: "<formatted table with row count, column headers, and data rows>"}]}'
• Enhance error responses with categorization and recovery hints. E.g., 'Refused: table "users" not in allowlist. Call describe_schema() to see available tables.' or 'Refused: syntax error in SQL. Check for missing commas or invalid column names.'
• Add tool annotations to TOOLS definitions: readOnlyHint: true and idempotentHint: true for both tools to signal safety to agents.
• Expand describe_schema description: 'List all tables and columns this server exposes. Call this first to discover available data before querying. Returns: table_name(column_name type, ...) format.'

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry