• insert to i
• update to u
• delete to d
• filter to q
• document to doc
• updateMods to mods

I think this is a good starting point to match existing insert/update/delete. After this change, we can do performance tests for some representative workloads before investing more in arguments space optimization.

Note that if we do shorten the names, we'll need to make sure to update the op size calculation logic on mongos added in SERVER-73536 since that will currently rely on the original argument names. (Edit: That logic was all written using the k____FieldName constants and so it should work even if the names change.)