[galaxy-dev] Tools accessing web services

Apologies in advance for the newbie question.

I have a script that uses various UniProt web services. The script sends off a request to the UniProt server, waits for it to be returned, and then writes the results to a file. This works fine as a standalone script, but when plugged into Galaxy, I get this error:

⇝ KeyError: 'GALAXY_URL' URL: http://127.0.0.1:8080/tool_runner/index

Does Galaxy "intervene" in the operation of all tools that access outside web services, and if so, do I need to rewrite the tool as one that acts as a data source (like the UCSC browser, biomart, etc.)? The data sources documentation did not mention whether this was necessary or not.

Thanks!