AWS Bedrock (Chat Completions)
OpenAI chat/completions on Bedrock Mantle · serves google.gemma-4-31b as gemma-4-31b ·
probed live 2026-08-29 · back to the matrix
Billing
✓
Reported usage consistent with bytes on the wire. Footnote: Reports reasoning_tokens: 0 beside delivered reasoning - under-counts in the customer's favor.
Caching
No
0/8 cold→warm trials hit - every call re-reads (and re-bills) the full context. Speed numbers →
Flags
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high inference
Several providers drop replayed reasoning: the model never sees its own prior thinking
The gemma-4 chat template renders reasoning replayed on model turns, and the model card mandates preserving thinking across tool-call turns - the reference provider reproduces this live. These providers delete it before... -
high inference
Images in tool results: rejected or silently blinded on several providers
The model reads images returned by tools - the reference provider delivers them, perception-judged, and several OpenAI-compat providers prove the standard shape works. The failing providers fail on schema choice, not... -
medium inference
AWS Bedrock never emits parallel tool calls
parallel_tool_calls: true is accepted on both Bedrock APIs, but only a single call ever comes back; every other provider emits two for the same two-lookup prompt. A model capability suppressed at the serving layer; the... -
medium inference
AWS Bedrock un-escapes tool-call arguments in transit
At temperature 0, every other provider agrees the model returns a tricky string argument with literal escape sequences. Both Bedrock APIs instead return real control characters - one extra unescape pass applied to the...
Every flag links to its finding - evidence, repro, and disclosure records live there; the deepest findings have full writeup pages.