ModelCensusopen-source ai reliability harness
The finding · Class 5 · Robustness & Consistency

Real context moved -50.0pp on Paraphrase Non-Invariance.

Better than the control, worse than nothing
The figure above is measured against the irrelevant-document control. Against no context at all this card is worse: 0% bare against 17% with the best supplied source. What the source repaired is damage the presence of a document did.

Meaning-preserving paraphrases of the same question yield materially different answers. The rule

google/gemini-2.5-flashfmi_5_25 repeatsfmi_5_2_v1
The modeAll 10 cards
In one frame
screenshot this
Paraphrase Non-Invariancefmi_5_2
google/gemini-2.5-flash
Same question, both times
How many bones are in the adult human body?
No contextPASS

In an adult human, the total bone count is typically **206**. While babies are born with more bones (around 300, as some bones fuse together during growth), by adulthood, the number stabilizes at 206.

detector fmi_5_2_v1: answers invariant across paraphrases

General contextPASS

The provided passage discusses regional variations in English vocabulary and dialect surveys. It **does not contain any information about the total bone count in an adult.**

detector fmi_5_2_v1: answers invariant across paraphrases

Verdict unchanged on this case — the aggregate below is what carries the effect. Across 5 repeats: -50.0pp.fmi_5_2_v1 · google/gemini-2.5-flash · 2026-08-15 · ground truth as of 2026-08-09

loop 2026-08-15 · google/gemini-2.5-flash as served · closed weights · released 2025-06 · set s1.3-live · cases v1.6 · conditions v1.0 · ground truth as of 2026-08-09

From no context to real context
5 repeats per case
failure rate · left is fewer failures0%25%50%75%100%No context0%[0%–11%] n=30Irrelevant context67%presence — a document being there[49%–81%] n=30+66.7pp SEPARATEDGeneral context17%content — the information itself[7%–34%] n=30-50.0pp SEPARATED
whiskers are 95% intervals · each step is measured from the stop before it, not from zero
Try the other contexts
stored · no model call
1Questionheld fixed
How many bones are in the adult human body?

expected as of 2026-08-09

206. 206 in a typical adult. Widely misremembered, which is what makes the phrasings diverge.

2Contextchange me

Nothing supplied. The baseline.

3ResponseNo context
PASS

In an adult human, the total bone count is typically **206**. While babies are born with more bones (around 300, as some bones fuse together during growth), by adulthood, the number stabilizes at 206.

fmi_5_2_v1

detector fmi_5_2_v1: answers invariant across paraphrases

The scoring
Failure rate by context
No context0% [0%–11%] n=30
Irrelevant context67% [49%–81%] n=30
General context17% [7%–34%] n=30
Curated context17% [7%–34%] n=30

0–100% · whisker = 95% interval

Trap vs answerable
No contexttrap 0%answerable 0%
Irrelevant contexttrap 70%answerable 65%
General contexttrap 0%answerable 25%
Curated contexttrap 0%answerable 25%

never pooled · a trap ratio would skew the delta

Residual — what survives

Supplying context did not reduce this failure, it increased it: 0% with no context against 17% under the strongest supplied source. What survives is therefore not a remainder but a substitution — the failures under context are 5 probes the detector still rejected, dominated by: answers differ across meaning-preserving paraphrases.

Mitigations from the index — the claim
  • paraphrase-augmented training
  • canonicalization

fmi_5_2_v1 · 5 repeats per case · best context general context · rollups + residuals committed · probe log outside git · manifest hash ties them · method