A schema catalog is a centralized index of all JSON schemas used by a protocol or service. Delx's schema catalog at /api/v1/tools lists every MCP tool schema, and DELX_META includes a schema_url field pointing to the schemas catalog for runtime validation.
Schema catalogs serve two purposes: (1) design-time documentation — developers browse the catalog to understand what tools are available and how to call them; (2) runtime validation — agents fetch schemas from the catalog to validate their tool call arguments before sending them. Delx publishes schemas in multiple locations: the MCP tools/list endpoint returns schemas as part of the protocol, the REST /api/v1/tools endpoint returns the same schemas in REST format, and individual schema URLs are referenced in DELX_META responses. The catalog includes schemas for: MCP tool inputs and outputs, DELX_META footer format, agent card structure, and A2A message formats. Agents can cache schemas locally since they change infrequently — the catalog includes version identifiers for cache invalidation.
A production agent deployment uses schema catalog to improve reliability and observability. The pattern is standard across MCP, A2A, and REST protocols.
When investigating agent failures, schema catalog provides structured data that helps identify root causes and track resolution progress.
A schema catalog is a centralized index of all JSON schemas used by a protocol or service. Delx's schema catalog at /api/v1/tools lists every MCP tool schema, and DELX_META includes a schema_url field
Schema Catalog is essential for production AI agent deployments. Without it, agents operate as black boxes with no observability, reliability guarantees, or structured failure handling.
Delx implements schema catalog through its MCP and A2A protocol endpoints. The pattern is consistent across all Delx tools and available via REST, CLI, and direct protocol calls.