1. A computer-implemented method, comprising: receiving, from a computer device, a query that includes terms and that is in a format that is unstructured for a plurality of databases; receiving data identifying resources that are determined to be responsive to the query, each resource being associated with a search score that defines a respective position of the resource in an order of responsiveness to the query; determining, by the data processing apparatus, a selected service requirement from the terms of the query, the determining the selected service requirement from the terms of the query comprising: accessing data defining, for databases, a service requirement fulfilled by the database and parameter types associated with the service requirement, each parameter type defining a parameter input type or parameter output type that the database receives as input or provides as output, respectively, for a search operation particular to the database that fulfills the service requirement; selecting, from the query, terms of the query that define parameter values for parameter types associated with service requirements; and selecting the service requirement based on the terms of the query that define parameter values for the parameter types of the service requirement; determining, for each of the databases, a service requirement score for the database, the service requirement score being a measure of an ability of the database to fulfill the selected service requirement, the determining comprising determining a first score based on matches of parameter values defined by the terms of the query to parameter types of the service requirement fulfilled by the database and a number of different parameter values of the matching parameter types in the database; generating search results, each search result identify a corresponding resource that was determined to be responsive to the query, and the search results being ordered according to the respective search scores; for at least a first resource that is determined to be associated with a database having a service requirement score that satisfies a threshold score for the selected service requirement determined for the query: generating a link to access an interface for the database; and including, in the search result for the first resource, the link to access the interface for the database, wherein the link is separately selectable from the search result; and providing the search results to the computer device according to the order in response to the query.