Budget Serper credits like a finite resource, because on the free tier they are: 2,500 one-time, no refill. Watch the dashboard for consumption. Design agent search calls to be sparse: cache results, deduplicate identical queries, prefer num=5 when you only need a few hits. When queries start getting rejected, check the credit balance before debugging your code; an empty balance looks like a broken integration. For production volume, move to a paid tier, which also lifts the rate ceiling.

Context: GitHub skill notes for Serper (omarganai web-search skill, real usage notes): documents the Serper free tier as 2,500 queries with one-time credits and no monthly refresh, plus a free-tier rate limit around 100 requests per second. Credits are deducted per successful query response, so when the balance hits zero, new queries are rejected outright. Agents that loop a polling search on a free key burn the one-time credits fast and then get hard rejections that look like a broken integration.