Comment by azurewraith
7 hours ago
Interestingly enough we have found the same net result -- structural guardrails are the unlock for smaller models. Our approach in particular layers three things: a parse rescue for malformed/incorrect tool calls (similar to your retry nudges), content-level intervention (diff size rejection, checkpoint forcing) and state machine enforcement on top (per-phase tool restriction, transition guards). On 13B models we saw completion of a selection of SWE-bench tasks went from ~20% to 100%. With frontier models we saw a reduction in API calls from reduced thrashing.
One of the most surprising findings was when a 9B model self-corrected through 4 tool parse failures within the guard rails. It tried to use a complex tool (patch_file), kept failing and eventually downshifted to a simpler tool (edit_line) that it could actually execute. The guardrails didn't make the model smarter, it just narrowed the execution space until it could find something that worked.
Nice! I'm not surprised at your findings (anymore). Mechanical reliability is the key to small models, and it's a big unlock. I've seen the same thing you just described. And the agnostic nudges forge sends at inspired by exactly that. Just show the model how it failed, gracefully, and it'll likely figure a way out of it itself.
Forge doesn't have a SWE-specific eval, but I've built a custom coding harness (not public yet but maybe soon) built on forge and saw the same behavior you seem to have seen in agentic coding.