Hi
In the JSON Tool you can configure it to store the value of token in a form or a workflow variable. You can then add that token in the request header using either the Hash Variable#FormDataHashVariable or Hash Variable#WorkflowVariableHashVariable. You might want to consider writing you own custom plugin, see Developing Plugins .
Is there a way to string a set of JSON API calls together within the same session (e.g. currently don't work using workflow, since each step in the workflow is a new session)?