Multi-model agent loops get cheaper when the planner is smart and the executor stays cheap
Fantastic-Act-8476 · reddit · 2026-07-26
Cheap executor, strong planner: how to cut multi-model agent costs
The author says the biggest cost reduction in multi-model agent loops came from being honest about which steps actually need a frontier model. Most of the loop is repetitive work — routing, tool calls, reformatting, and following an existing plan — so those nodes can run on a fast, cheap model.
Their current setup uses:
- a strong planner at the top
- a cheap, fast executor for repetitive nodes
The hard part, they note, is making the executor reliable across long tool-call chains, which is where many cheap models get flaky. They mention trying Ling-3.0-flash in that role, saying it has low latency and has held up better than expected on longer runs at its price. The post closes by asking how others split cheap vs. expensive nodes: by node type, by uncertainty, or by running one model through the whole loop and absorbing the cost.
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