Google Cloud API Gateway can now accept MCP JSON-RPC on /mcp and map tools/call to existing REST operations. Teams opt in through an OpenAPI 3.0 or 3.1 extension and reuse the API's JWT or API-key authentication, quotas and logs. The public preview supports up to 1,000 tools, but not resources, prompts, response streaming or Model Armor inspection. Tool discovery is unauthenticated by default and requires explicit JWT protection in production; API keys cannot protect tools/list.
Google API Gateway exposes existing REST APIs as MCP tools
2026-09-24Verified announcementTRIAL
Google Cloud API Gateway can now accept MCP JSON-RPC on /mcp and map tools/call to existing REST operations. Teams opt in through an OpenAPI 3.0 or 3.1 extension and reuse the API's JWT or API-key authentication, quotas and logs. The public preview supports up to 1,000 tools, but not resources, prompts, response streaming or Model Armor inspection. Tool discovery is unauthenticated by default and requires explicit JWT protection in production; API keys cannot protect tools/list.
Referencedevelopers.googleblog.com · turn your rest apis into mcp tools with google cloud api gatewayDocumentationcloud.google.com · mcp toolbox
Availability: Public Preview
Imported from the existing research archive. Migration preserves the recorded judgment and is not a fresh verification.
What this means for you
For teams with governed REST APIs, this can remove a second MCP server layer. The hard part moves to safe discovery metadata and policy configuration: protect tools/list, expose only necessary operations, and do not assume the preview inspects payloads or supports streaming.
Evidence & related material
Technical details & scores
| Availability | Public Preview |
|---|---|
| Mapping | MCP JSON-RPC /mcp and tools/call to REST operations |
| Configuration | OpenAPI 3.0/3.1 x-google-api-management.mcp; OpenAPI 2.0 unsupported |
| Limit | up to 1,000 tools |
| Security | tools/list unauthenticated by default; explicit JWT protection required; API keys unsupported for discovery |
| Unsupported | resources, prompts, response streaming, Model Armor payload inspection and shared MCP/model-routing configs |
Technical impact 4
Engineering value 5
Adoption signal 4
Maturity 2
Verification cost 2
Risk 3