MessageHeader resource (FHIR R4)

MessageHeader is the FHIR R4 resource for the header for a message exchange that is either requesting or responding to an action.

Resource	MessageHeader
FHIR version	R4 (4.0.1)
Canonical URL	http://hl7.org/fhir/StructureDefinition/MessageHeader
Required elements	event[x] (1..1), source (1..1)

Example

{
  "resourceType": "MessageHeader",
  "id": "messageheader-a5830b6b12b3f9b7c21383606fd3f2ab",
  "eventCoding": {
    "system": "http://example.org/pidgeon/synthetic"
  },
  "source": {
    "endpoint": "http://example.org/pidgeon/synthetic"
  }
}

Generated by the Pidgeon engine: pidgeon generate MessageHeader --seed 20260722.

Validation context

strict pidgeon validate grades a MessageHeader instance against the base R4 structure definition: missing required elements raise REQUIRED_FIELD_MISSING and cardinality violations raise CARDINALITY_MIN or CARDINALITY_MAX.(REQUIRED_FIELD_MISSING)

This answer, in your terminal

pidgeon lookup MessageHeader

Wire it into your AI agent:

claude mcp add pidgeon -- npx -y @pidgeonhealth/mcp

Download Post free to browse this reference with generation attached.