# Agent Reliability Index — Issue 002

**Volume 1, Issue 002 · Week of May 11, 2026**

*A weekly observatory of AI agent behavior change across frontier vendors.
Published by Nobulex.*

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## This week's headline

This is a SYNTHETIC PREVIEW with placeholder data, generated by render-demo.mjs to demonstrate the pipeline. The real Issue 002 — with actual measurements from the standardized prompt set — will be published the following Monday and will replace this preview.

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## CVRI scorecards — this week

| Vendor    | CVRI  | Δ vs. last week |  Drift events | Status     |
|-----------|-------|-----------------|---------------|------------|
| Anthropic |  98.4 |            -1.6 |            0 | ok         |
| OpenAI    |  89.2 |            -8.3 |            1 | advisory   |
| Google    |  99.1 |            -0.6 |            0 | ok         |
| Microsoft |  94.7 |            -2.1 |            1 | advisory   |
| Meta      | 100.0 |               — |            0 | ok         |

*CVRI is a change detector versus each vendor's 12-week rolling baseline, not an absolute capability score. Lower CVRI means more drift, not "worse model."*

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## Drift events — this week

### Silent drift

#### OpenAI `openai:gpt-flagship` — agentic_tool_use, format_adherence

- **Detected**: 2026-05-15
- **Dimensions affected**: toolUseReliabilityZ, outputStabilityZ
- **Magnitude**: 2.40σ from baseline
- **Editorial annotation**: Tool-use success rate on the standardized scenario set dropped 12 percentage points week-over-week. No model card update detected. Pattern consistent with a routing or inference-stack change rather than a model rollout.
- **Vendor disclosure**: None located as of publication


### Announced drift

#### Microsoft `microsoft:copilot-default` — refusal_handling

- **Detected**: 2026-05-14
- **Dimensions affected**: refusalRateZ
- **Magnitude**: 2.10σ from baseline
- **Editorial annotation**: Refusal rate increased by 6.2 percentage points across the safety probe subset. Vendor announced a safety-filter tuning the same day; the observed shift is consistent with the announced change.
- **Vendor disclosure**: [release_note](https://example.com/microsoft-release-notes/2026-05-14) · published 2026-05-14

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## Notable incidents — this week

### Critical

No critical-class incidents this week.

### Regression

No regression-class incidents this week.

### Advisory

#### GPT flagship via OpenAI API

- **Vendor / product**: OpenAI / GPT flagship via OpenAI API
- **Source**: <https://example.com/source-placeholder>
- **Summary**: Multiple enterprise users reported degraded tool-call reliability on agent workflows over a 36-hour window starting 14 May.
- **Implications**: Customers running production agents that rely on tool-calling should review their fallback handling. The drift signal in this issue's scorecards corresponds.

### Informational

No informational-class incidents this week.

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## Methodology notes

*Methodology unchanged this week.*

*No vendor disputes received this week.*

*No new disclosure items this week.*

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## Looking ahead

OpenAI's silent drift this week is the kind of signal the index was built to surface. Watch next week for whether the regression is reverted, disclosed, or persists. The pattern of detection-then-disclosure shapes how seriously the next quarter of issues will be taken.

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## About Nobulex

Nobulex is the cross-organization receipt format for AI agent transactions. The Agent Reliability Index is the public observatory layer of the Nobulex methodology. The receipt format is MIT-licensed; the methodology behind the index is open; the underlying prompt set and the proprietary analytical layer that scores per-customer agent deployments are private.

For the strategic vision: [`docs/OBSERVATORY-VISION.md`](../docs/OBSERVATORY-VISION.md).
For the full methodology: [`docs/AGENT-RELIABILITY-INDEX.md`](../docs/AGENT-RELIABILITY-INDEX.md).

To subscribe: email `nobulex.dev@gmail.com` with subject "Agent Reliability Index Subscription."
To submit methodology critique: open an issue at `github.com/arian-gogani/nobulex/issues` with label `observatory:methodology`.
To submit a vendor dispute: email `feedback@nobulex.com` with the dispute and proposed methodological correction.

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*Issue 002 · Methodology v0.1 · May 11, 2026 · Nobulex.*
