Efferent coupling

What it means

Efferent coupling measures how many external components a target component depends on. It describes outward knowledge and can indicate integration breadth, setup burden, or potential failure paths. A high value may be appropriate for an orchestrator, but it deserves attention when concentrated in business-critical code.

Example

A service coordinator calls identity, inventory, pricing, tax, and notification modules. Mapping its outward dependencies helps the team decide which calls need timeouts, contracts, or a narrower application boundary.

Limitations

The count ignores dependency weight and runtime frequency. A component with two critical remote dependencies may be riskier than one with ten local helpers. Treat the metric as a map of relationships, not a reliability measurement.

How to use the signal

Inspect whether outward relationships are local, remote, optional, or failure-sensitive before treating the count as architectural risk.

Weave can help compare high-efferent changes with queue time, review iteration, and incidents. Keep latency and failure evidence in observability systems, and use this architecture signal to focus the investigation.