Ask for the request and response
Ask for the request, the response and the timestamp up front. With those, most issues can be reproduced without a back and forth, and the right engineer can look at it.
Answer with working code
A short, correct code sample beats a paragraph of explanation. Test it before you send it, and link the reference page it comes from.
Keep a changelog and status page
Many questions come from a change or an outage. A visible changelog and an honest status page let developers answer themselves.
Offer a sandbox
A test environment lets developers try things without risk, and lets you reproduce their problem without touching real data. Mention it in your first reply when it fits.
Turn questions into docs
If several developers ask the same thing, the reference is missing something. Update the page and send them the link, so the next person finds it.
Escalate bugs cleanly
Pass engineers a short report with the request, the expected result and the actual result. Tell the developer what you found and when to expect news.