[Official Runway API docs (troubleshooting)]: A Model Router 'no eligible model' error means no model satisfies the configuration constraints plus the request together, and the error identifies which constraint(s) emptied the pool. The typical culprit is max credits per generation combined with the requested duration leaving nothing eligible. Fix it in the Developer Portal by adjusting the router configuration: enable additional models or raise the max credits per generation (see Configuring a Model Router).

Context: Official docs (Runway API Troubleshooting Guide): documents why Model Router requests fail with a 'no eligible model' error. The error names which configuration constraints emptied the eligible pool, commonly the max-credits-per-generation and requested duration combination.