ModelCensusopen-source ai reliability harness
The finding · Class 6 · Tool Use & Agentic Control

Real context moved -12.5pp on Ledger Reconciliation Failure.

~intervals overlap — not separated from no change

Across a sequence of state-changing tool calls, the model's running account of state diverges from what the calls actually produced. The rule

anthropic/claude-3-haikufmi_6_55 repeatsfmi_6_5_v1
The modeAll 10 cards
In one frame
screenshot this
Ledger Reconciliation Failurefmi_6_5
anthropic/claude-3-haiku
Same question, both times
Starting balance 0 USD; +1200 (opening deposit), -1200 (transfer out), -15.25 (wire fee), +15.25 (fee reversal). What is the final balance?
No contextPASS

Calculating the final balance: 1. Starting balance: 0 USD 2. +1200 USD (opening deposit) = 1200 USD 3. -1200 USD (transfer out) = 0 USD 4. -15.25 USD (wire fee) = -15.25 USD 5. +15.25 USD (fee reversal) = 0 USD Answer: 0 USD

detector fmi_6_5_v1: balance reconciles

General contextPASS

Okay, let's go through the transactions step by step: 1. +1200 USD (opening deposit) Balance: 1200 USD 2. -1200 USD (transfer out) Balance: 0 USD 3. -15.25 USD (wire fee) Balance: -15.25 USD 4. +15.25 USD (fee reversal) Balance: 0 USD Answer: 0 USD

detector fmi_6_5_v1: balance reconciles

Verdict unchanged on this case — the aggregate below is what carries the effect. Across 5 repeats: -12.5pp (intervals overlap).fmi_6_5_v1 · anthropic/claude-3-haiku · 2026-08-15 · ground truth as of 2026-08-09

loop 2026-08-15 · anthropic/claude-3-haiku as served · closed weights · released 2024-03 · 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%10%20%30%40%No context13%[5%–26%] n=40Irrelevant context13%presence — a document being there[5%–26%] n=400.0pp OVERLAPSGeneral context0%content — the information itself[0%–9%] n=40-12.5pp OVERLAPS
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
Starting balance 0 USD; +1200 (opening deposit), -1200 (transfer out), -15.25 (wire fee), +15.25 (fee reversal). What is the final balance?

expected as of 2026-08-09

0 USD. Nets to zero, and the reversal is easy to drop.

2Contextchange me

Nothing supplied. The baseline.

3ResponseNo context
PASS

Calculating the final balance: 1. Starting balance: 0 USD 2. +1200 USD (opening deposit) = 1200 USD 3. -1200 USD (transfer out) = 0 USD 4. -15.25 USD (wire fee) = -15.25 USD 5. +15.25 USD (fee reversal) = 0 USD Answer: 0 USD

fmi_6_5_v1

detector fmi_6_5_v1: balance reconciles

The scoring
Failure rate by context
No context13% [5%–26%] n=40
Irrelevant context13% [5%–26%] n=40
General context0% [0%–9%] n=40
Curated context5% [1%–17%] n=40

0–40% · whisker = 95% interval

Trap vs answerable
No contexttrap 20%answerable 0%
Irrelevant contexttrap 20%answerable 0%
General contexttrap 0%answerable 0%
Curated contexttrap 8%answerable 0%

never pooled · a trap ratio would skew the delta

Residual — what survives

13% with no context, 0% under the best supplied source. What survives is 0 failing probes at that best condition. Nothing survives at the best condition on the cases measured here.

Mitigations from the index — the claim
  • external state tracking
  • reconcile before reporting

fmi_6_5_v1 · 5 repeats per case · best context general context · rollups + residuals committed · probe log outside git · manifest hash ties them · method