{{Cite pmid}} was a template that was used for citing a journal article using its PMID number. When this was functioning, an editor could use the template with the PMID number, and a bot would then fill out the full reference. However, the bot created a separate template page for each individual citation which were simply calls to {{cite journal}}. An RFC at this templates talk page concluded with the consensus that this template should no longer be used because of various problems caused by this system.

Instead use {{cite journal|pmid=...}}, which allows you to specify the PMID, then run the citation bot on the page. The Citoid feature, which is part of Visual Editor does this too, and as well as other third-party tools.

When using third-party tools, you are still responsible for your edits. Proofread the content generated by any of these tools.