So you want to use OpenRouter?

Choosing a model through OpenRouter also involves choosing among companies that serve it. In a firsthand production account, developer Mo Moustafa reports provider-dependent failures such as tool instructions arriving as ordinary text and successful HTTP responses containing no usable answer. Those failures occur at the service interface an application consumes.

OpenRouter's routing documentation explains one relevant control: require_parameters can restrict requests to providers that support every requested parameter. Without that requirement, unsupported parameters can be ignored. Together, the documentation and reported failures show why testing a model name alone is insufficient: an application's behavior also depends on the selected provider and routing settings.