DataDC MCP has well-structured tool definitions with complete input schemas and clear descriptions. All three tools (dc_recent, dc_layers, dc_query) follow verb_noun naming and include parameter type definitions. However, output schemas are not documented, the code returns structured objects but LLMs cannot see what fields to expect. Error handling is minimal (only basic ArcGIS error checks). Parameter descriptions are good but lack explicit constraints (e.g., 'limit 1-1000' is stated in dc_recent but not enforced in dc_query). No tool annotations (readOnlyHint, etc.) despite all being read-only operations.

• Document output schemas for all three tools. Specify that dc_recent returns {dataset, label, service, layer, sorted_by, count, source, rows: [{...}]}, dc_layers returns {services: [{name, path}]} or {layers: [{id, name}]}, and dc_query returns {count, rows: [{...}]}.
• Add readOnlyHint: true to all tool definitions in the McpToolDefinition interface. This signals to agents that these operations are safe to retry and have no side effects.
• Enhance error messages with recovery guidance. Instead of 'DC ArcGIS: 404', return 'Service not found. Verify the service path (e.g., FEEDS/MPD/MapServer) using dc_layers, or use a known short name (crime, service_requests, permits).'
• Add JSON Schema constraints (minimum, maximum, pattern) to parameters. For dc_query.limit, add minimum: 1, maximum: 2000. For dc_recent.limit, add minimum: 1, maximum: 1000.
• Document the response structure of dc_layers when service is omitted. Clarify whether it returns a list of service names, full paths, or a nested object with service metadata.