# Migrating MCP integrations MCP is now a [first-class binding](https://autoagentprotocol.org/docs/v3.0/bindings/mcp.md). Implement it directly against shared automotive services, or adapt an existing A2A backend. | Earlier reference catalog | AAP 3.0 | |---|---| | Remote `$ref` as the tool's entire input schema | Complete object schemas with bundled `$defs` | | No output schema | Typed success/error union in `outputSchema` | | Custom AAP keys in `annotations` | Standard behavior hints; namespaced AAP `_meta` | | Wrapper assumed to call A2A | Direct implementation or adapter | | One old MCP revision | Current 2026-07-28 and 2025-11-25 client compatibility | | Optional lead retry key | Required idempotency key and shared duplicate suppression | Keep the `aap_*` tool names. Arguments still carry the typed AAP request, including `type`; results carry the matching response in `structuredContent` and serialized JSON text. Publish the same actual skill subset and inventory capabilities through every binding. Update dealer-domain discovery and `/llms.txt` to point to the deployed MCP endpoint. The downloadable catalog is not that endpoint. A PAP `apis` entry for MCP additionally requires native PAP session authorization; an ordinary public MCP endpoint belongs in the AAP discovery extension until that support exists. See the [MCP binding](https://autoagentprotocol.org/docs/v3.0/bindings/mcp.md) for exact envelopes, headers, error handling and authorization, and [inventory search](https://autoagentprotocol.org/docs/v3.0/skills/inventory-search.md) for the new search contract.