Hidden third-party agents restore efficiency in contracts, preventing renegotiation issues.
The introduction of a hidden third-party agent in certain situations can help solve problems in contracts without risking collusion. This agent is only revealed off-equilibrium and with some probability, and its existence and identity are unknown to others. In many real-world cases, this hidden agent can restore the efficient allocation of resources. If this agent doesn't know the full picture, there's a way to make sure the plan works.