CDS Hooks is an HL7 specification for real-time clinical decision support delivered through a workflow-triggered API. As a clinician works in an EHR, defined hooks (patient-view, order-select, order-sign, appointment-book) fire a request to an external CDS service, which returns 'cards' — suggestions, warnings, links, or SMART app launches — rendered inline in the workflow. It lets decision logic live outside the EHR yet appear at the moment of care.
CDS Hooks
CDS Hooks is the standard that lets clinical guidance live outside the EHR and still show up exactly when a decision is being made. Rather than baking every rule into the record system, an EHR fires a hook at defined moments — viewing a patient, selecting an order, signing it — and an external service answers with cards the clinician sees inline.
- Workflow-triggered, not polled - Hooks (
patient-view,order-select,order-sign,appointment-book) turn the EHR into an event source, calling out at the point of care. - Cards as the response - A service returns suggestions, warnings, informational links, or a SMART app launch, so guidance can escalate from advice to action.
- Composes with FHIR + SMART - Cards reference FHIR resources and can hand off to a SMART on FHIR app, tying decision support to the same authorization model.
CDS Hooks matters to how I read agent-readiness because it is one of the only genuinely reactive healthcare contracts — an event surface a system can subscribe to rather than a static endpoint it must poll. In a sector where webhooks and FHIR Subscriptions are rare, a real CDS Hooks implementation signals a provider that has thought about being called by other software, which is the same posture an agent needs.
Referenced in API Evangelist papers
This standard shows up in my published research. These reports read the machine-readable evidence provider by provider — and put this standard in the context of a real sector.
The State of US Healthcare APIs
Epic's CDS Hooks surface is one of the few genuinely reactive, event-driven artifacts among the incumbent EHRs.
