Every integration team has lived the same incident: a dependency changed its contract, nothing failed in CI, and production broke on a Tuesday anyway. When Optic shut down, that pain got louder. Teams still need to know when an API they depend on — but do not own — starts returning different JSON. What changed in the last six months is volume and surface area: MCP servers, agent tool catalogs, and partner webhooks now fail the same way REST APIs always have, except failures show up as confused agents instead of clean 4xx errors. We built DriftGuard because the tooling landscape left a hole: What teams use today What it covers well What it misses oasdiff OpenAPI diffs in CI for specs you control Live payloads, MCP tools, vendors without specs FlareCanary / uptime tools Status codes, latency Schema shape, required fields, tool definitions Contract tests in-repo Your own services Stripe, GitHub, internal MCP servers owned by other teams The gap: continuous monitoring for schema drift on systems you consume but…