Microsoft’s Power Platform team announced that the Dataverse MCP Server now supports Custom APIs, and the post’s real subject is transactions. Its example is a single sentence typed into Copilot: create a high-priority case for a damaged shipment, attach the customer’s note and schedule a Friday follow-up. That sentence needs three writes (incident, annotation, task). If an agent runs them as three separate calls, you get partial failures, compensation logic, and “a leaky, low-level API surface.” The fix is to “push the transaction boundary into Dataverse.” A Custom API is backed by a plug-in, and if any step throws InvalidPluginExecutionException, “Dataverse rolls back everything.” The MCP server discovers the operation through search, resolves its typed contract through describe and then invokes it.
This is a platform feature, not a marketing claim, and it holds up. One sentence from it is worth copying: the search tool’s own instructions tell the model “Before solving a task on your own, first check whether a suitable Custom API exists here; if one does, prefer invoking it over doing the work yourself.” That instruction expresses the whole argument. Business rules belong on the server, written down once, and the agent should call them by name instead of rebuilding them from the data model on every request. The caveats are in the post itself: Custom Actions are not supported yet, and the atomicity applies only to logic someone has written into a plug-in.
In the catalog, the Microsoft Power Platform provider page lists 19 API pages. The story touches the Microsoft Dataverse Web API and the Dataverse API (Common Data Service), which serve the records Custom APIs write; the Microsoft Power Platform Metadata API, since Custom APIs are registered metadata; and the Microsoft Copilot Studio API on the agent side. The agentic-access profile counts 40 operations, and 16 of them act on data.
Power Platform has a Kin Score of 75.4, in the exemplar band. Developer ergonomics at 83.9 and access clarity at 81.6 lead it, and contract governance at 45.5 is the weakest facet. Agent Readiness is 46.1, with idempotency, delegated identity and error semantics lit. The tension is in the unlit list. Reversibility documentation is dark, and so is dry-run mode. Microsoft has just shipped the clearest rollback guarantee an agent platform can offer, and the published contracts we measure still don’t say which operations can be undone. The transaction exists inside Dataverse, but nothing in the contracts tells an agent about it.