Multi-agent SaaS: 15x cost variance between runs
A B2B SaaS team shipped an autonomous research agent that chains planning, search, and drafting sub-agents. Two identical user requests could cost $0.80 or $12.40 depending on which models the router picked and how many search loops the planner triggered.
before
$31,000 / month
after
$8,200 / month
the fix
Synapse proxy tagged every agent step by model and tool. The team set a 4-step hard cap on the planner loop and routed summarization to a smaller model. Variance dropped from 15x to under 2x.
Lever: Model-router attribution + hard step budget