Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add rules/duckduckgo/apple-browsers/network-quality-variance-scoringgit clone --depth 1 https://github.com/duckduckgo/apple-browsersWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/rules/duckduckgo/apple-browsers/network-quality-variance-scoring)<a href="https://agentmods.dev/rules/duckduckgo/apple-browsers/network-quality-variance-scoring"><img src="https://agentmods.dev/badge/rules/duckduckgo/apple-browsers/network-quality-variance-scoring.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00000 | $0.00899 |
| Opus 5 | $0.00000 | $0.00449 |
| Sonnet 5 | $0.00000 | $0.00180 |
| Haiku 4.5 | $0.00000 | $0.00090 |
Grade A, and why
network-quality-variance-scoring scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 104 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Network Quality Variance Scoring Using Coefficient of Variation
Overview
NetworkQualityMonitor displays variance in milliseconds (user-friendly) but scores using Coefficient of Variation (CV) internally. This provides fair comparison across different latency ranges.
Display vs Scoring
- UI Display: Shows variance in milliseconds (e.g., "5.2 ms (10.4%)")
- Internal Scoring: Uses CV = (stdDev/mean) × 100 for penalties
- Quality Labels: Based on CV percentage thresholds
Why CV for Scoring?
A 10ms variance means different things at different latencies:
- 10ms variance on 50ms latency = 20% CV (moderate issue)
- 10ms variance on 200ms latency = 5% CV (excellent consistency)
Using CV ensures fair scoring regardless of base latency.
CV Thresholds and Test Iterations
| CV Range | Quality | Penalty | Test Iterations | Testing Impact |
|---|---|---|---|---|
| <10% | Excellent | 0 pts | ~30 iterations | Quick reliable tests |
| 10-20% | Good | -20 pts | ~100 iterations | Reasonable test time |
| 20-40% | Fair | -40 pts | ~400 iterations | Lengthy test cycles |
| >40% | Poor | -60 to -80 pts | 1000+ iterations | Practically unreliable |
Implementation
// Display shows milliseconds
value: String(format: "%.1f ms", responseVariance)
// Quality label uses CV internally
let cv = (variance / avgResponseTime) * 100
if cv < 10 { return "Excellent" }
else if cv < 20 { return "Good" }
else if cv < 40 { return "Fair" }
else { return "Poor" }
// Scoring penalty based on CV
switch coefficientOfVariation {
case ..<10: penalty = 0
case 10..<20: penalty = 20
case 20..<40: penalty = 40
case 40..<60: penalty = 60
default: penalty = 80
}
Statistical Analysis
Smart Warm-up Phase:
- Initial "cold" request to each endpoint (DNS resolution, TLS handshake)
- These measurements are discarded to eliminate first-request bias
- Ensures subsequent measurements reflect warm connection performance
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 4d ago First seen · 104 lines · 0 tokens per session scan A 6463643a23c8
network-quality-variance-scoring is a cursor rule published in the GitHub repository duckduckgo/apple-browsers (251 stars, last pushed today), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 899 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-01.
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