YugabyteDB MCP server demonstrates solid foundational quality with three well-named, action-oriented tools (summarize_database, run_read_only_query, run_write_query). All tools have clear descriptions (100-200 chars range, within baseline 194 char average) and properly typed input schemas with parameter descriptions. However, there are significant gaps in output schema documentation, error handling guidance, and parameter constraint enforcement that prevent this from reaching 70+. The server lacks documented output schemas (HARD requirement per pattern:tool), and error responses are not shown to include recovery guidance. Parameter descriptions exist but lack explicit format constraints, ranges, and enum values that would enable robust LLM reasoning. The write tool notably lacks a dry-run/confirmation pattern despite operating on destructive operations. Security controls (OIDC auth, guardrails, role-based execution) are well-designed but not reflected in tool annotations or error responses.

• Add explicit output schema documentation to each tool. E.g., for summarize_database: 'Returns {tables: [{name: string, columns: [{name: string, type: string, nullable: boolean}]}]}, total_count: number}'. This is required per pattern:tool.
• Enhance error responses with recovery guidance. When run_write_query is blocked, include the reason (e.g., 'Query blocked: DROP TABLE not allowed') and suggest an alternative (e.g., 'Use DELETE instead, or contact an admin to grant DDL permissions').
• Add a dry_run parameter to run_write_query (boolean, default false). When true, parse and validate the query but do not execute. Return a summary of affected rows/tables. This implements pattern:confirmation-request for destructive operations.
• Document guardrail constraints in run_write_query parameter description. E.g., 'SQL write query (INSERT, UPDATE, DELETE). Validated against blocklist: DROP, TRUNCATE, GRANT, REVOKE, CREATE/ALTER TABLE. Must include WHERE clause for UPDATE/DELETE unless mode='force' (requires elevated permissions). For full list, call summarize_database to understand schema first.'
• Add readOnlyHint and destructiveHint tool annotations. Mark summarize_database and run_read_only_query with readOnlyHint=true; mark run_write_query with destructiveHint=true. This signals intent to clients and agents.
• Enhance requested_role parameter description to include discovery guidance: 'Optional database role to assume (requires OIDC auth). Call summarize_database with requested_role=null to list available roles for your token, then select one.' Include an example error message: 'Role admin not found. Available roles: readonly, analyst, data-engineer.'

Inferred effective spec: 2026-07-28+.

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