An arXiv paper introduces SpecAgent, a collaboration protocol that turns a strong model from the author of each agent step into the reviewer of steps drafted by a weaker model. The weak model executes read-only tool calls while drafting so each step is grounded in real observations, and stops at the first action that would modify the environment; the strong model then verifies the drafted segment in a single prefill pass, commits the longest prefix it judges semantically valid, and repairs the first rejected step. The authors report SpecAgent comes within one point of the strong model's success rate on τ²-Bench while roughly halving memory traffic and wall time, recovers 44–75% of the quality gap on AutomationBench and VitaBench, and in an edge-cloud MCP-Atlas deployment closes 53–75% of the weak-strong quality gap with the strong model generating at most half as many tokens.

SpecAgent·arXiv·τ²-Bench·+3