MCP + A2A

Agent completion is not outcome finality.

MCP tool success and A2A task completion are accepted as execution evidence. Finality then reads the buyer-designated authoritative source and reconciles the ending.

Developer Quickstart Outcome Finality

Boundary

Execution acknowledgement stays downstream of authority and upstream of finality.

No agent protocol is treated as the authoritative system of record merely because it reports success.

MCP

tools/call success → EXECUTION_ACKNOWLEDGED → authoritative reconciliation

A2A

task completed → EXECUTION_ACKNOWLEDGED → authoritative reconciliation

Finality

Only the declared evidence contract can support FINAL; contradiction can REOPEN.