In this paper we describe a collaborative agent-based framework that allows service providers to monitor and evaluate component reliability using reports of the results of composed service executions. In the framework, service providers share reliability data with each other to mutually maintain the reliability of their services and protect them from unreliable components. Consumers rate success or failure of the composed service after each transaction. In service environments, providers can utilise component services offered by other providers to create new enterprise services. Therefore, a distributed component service can be executed simultaneously by several composed services. Since a composed service is offered as an integrated service, it is not possible for consumers to directly recognise a component that causes the service to fail. Collaborating agents use the association between component and composed services to monitor the reliability of the components and identify those that are unreliable.