Claude Opus 5.5 vs GLM-5.3 Flash (Workers AI)
Reading a 26.2K-token pull request costs $0.1048 on Claude Opus 5.5, 27× the $0.0039 it costs on GLM-5.3 Flash (Workers AI). Claude Opus 5.5 is a frontier model and GLM-5.3 Flash (Workers AI) a economy one. In the benchmark Claude Opus 5.5 caught 29 percentage points more of the known defects than GLM-5.3 Flash (Workers AI) (95% interval +18 pts to +41 pts, a − b).
Side by side
| Figure | Claude Opus 5.5 | GLM-5.3 Flash (Workers AI) |
|---|---|---|
| Price tier | Frontier | Economy |
| Bugs caughtshare of known bugs | 90% (better) | 61% |
| False alarmsper clean PR | 1.7 (better) | 1.8 |
| Cost per reviewmeasured | $0.1525 | $0.0035 (better) |
| Cost per bug caught | $0.1921 | $0.0066 (better) |
| Exact linecatches on the expected lines | 89% (better) | 89% |
| Review timemean | 33s (better) | 254s |
| Typical review calllist price | $0.1532 | $0.0051 (better) |
| Input / 1M tokens | $4.00 | $0.15 (better) |
| Output / 1M tokens | $20.00 | $0.50 (better) |
| Context window | 1M | 1M |
Head to head
The known bugs both were scored on, by who caught each in at least one run.
By language
| Model | All | TypeScript6 bugs | Go4 bugs | Java4 bugs | Rust4 bugs | C#3 bugs | JavaScript3 bugs | Kotlin3 bugs | PHP3 bugs | Python3 bugs | Ruby3 bugs | Swift3 bugs | C++2 bugs | C1 bug |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Claude Opus 5.5 | 90% | 100% | 50% | 78% | 100% | 100% | 100% | 67% | 100% | 100% | 89% | 100% | 100% | 100% |
| GLM-5.3 Flash (Workers AI) | 61% | 57% | 31% | 45% | 88% | 30% | 67% | 89% | 33% | 78% | 67% | 67% | 100% | 67% |
Of the 42 known bugs both were scored on, both caught 34 and neither caught 2. Claude Opus 5.5 caught 5 bugs that GLM-5.3 Flash (Workers AI) missed: 2 in PHP, 2 in TypeScript and 1 in C#, most of them logic bugs. GLM-5.3 Flash (Workers AI) caught one bug that Claude Opus 5.5 missed: 1 in Kotlin.
On pull requests with no known bug, Claude Opus 5.5 raised 1.7 false alarms per review and GLM-5.3 Flash (Workers AI) 1.8. A measured review cost $0.1525 on Claude Opus 5.5, 43× the cost of $0.0035 on GLM-5.3 Flash (Workers AI).
| Pull request | Language · kind | Claude Opus 5.5 | GLM-5.3 Flash (Workers AI) |
|---|---|---|---|
| TanStack/queryfix(query-core): fix hydration bugs for already resolved promises | TypeScript · Logic | 1/1 | 0/4 |
| colinhacks/zodfeat(v4): parse input containing reference cycles | TypeScript · Resource handling | 1/1 | 0/4 |
| doctrine/ormFix collection filtering API for IN/NOT IN comparisons that require type conversions | PHP · Logic | 1/1 | 0/3 |
| dotnet/orleansfix(serialization): cap codec allocations | C# · Logic | 1/1 | 0/3 |
| symfony/symfony[Security] Allow multiple OIDC discovery endpoints | PHP · Security | 1/1 | 0/3 |
| kotest/kotestFix DataClassEq comparator | Kotlin · Logic | 0/1 | 2/3 |
Defects caught over all runs: a PR reviewed three times with one known bug shows 3/3 when it was caught every time.
Every bug each was scored on: Claude Opus 5.5 and GLM-5.3 Flash (Workers AI).