1. A computer system for automatically generating service documentation based on usage of a web service, the computer system comprising: a processor configured to execute computer-executable instructions; and memory storing computer-executable instructions configured to: capture network traffic including actual requests to a service endpoint of the web service and actual responses from the service endpoint of the web service; analyze captured network traffic to determine one or more operations that are available at the service endpoint, input arguments that are accepted by the service endpoint, and output arguments that are provided by the service endpoint; generate metadata for the service endpoint that identifies the one or more operations, the input arguments, and the output arguments; automatically generate service documentation for the web service based on the metadata; and communicate the service documentation for the web service to a client device.