# How GPT-5.6 sol token is used in Codex

> Published 2026-07-21 · https://www.promptzone.com/yohjituralab/how-gpt-56-sol-token-is-used-in-codex-11d7

Disclosure: I maintain Tura, where the full test record is published.

I ran 280+ Codex CLI sessions with GPT-5.6 Sol. In the current build, fewer commands per model turn can mean more turns and more cached-input cost.

Most benchmarks favor 5.6 Sol on cost per result: on DeepSWE, 5.5 High averaged USD 5.1 per task versus USD 3.5 for 5.6 Sol High. But in Codex CLI 0.144.1, my 5.6 Sol High runs were about 21% more expensive than 5.5 High.

![How GPT-5.6 sol token is used in Codex](https://preview.redd.it/how-gpt-5-6-sol-token-is-used-in-codex-v0-pghf32p14meh1.png?width=1080&crop=smart&auto=webp&s=1b501ae165714278d0e824a224f72fcb4dc730be)

![How GPT-5.6 sol token is used in Codex](https://preview.redd.it/how-gpt-5-6-sol-token-is-used-in-codex-v0-esic3oac7meh1.png?width=1080&crop=smart&auto=webp&s=ffc29d6fdd8f3123f5eaec520889b470f1a9c406)

The likely mechanism is orchestration: 5.5 explicitly uses `multi_tool_use.parallel`, while 5.6 mainly uses one top-level `exec`. I observed 0.97 versus 2.5 commands per model call, roughly 1.84× as many rounds, and 66.5% of 5.6 Sol High cost in cached input. Token-saving plugins did not materially lower that total; reducing unnecessary model rounds did.

Implementation reference: https://github.com/openai/codex/blob/rust-v0.144.1/codex-rs/core/src/tools/code_mode/execute_handler.rs#L20-L72

Full test record: https://turaai.net/docs#benchmark-current-test-set-record