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 skills/nucliweb/webperf-snippets/webperf-interactionnpx skills add nucliweb/webperf-snippets --skill webperf-interactiongit clone --depth 1 https://github.com/nucliweb/webperf-snippetsWhat 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 | $0.00124 | $0.02797 |
| Opus 5 | $0.00062 | $0.01399 |
| Sonnet 5 | $0.00025 | $0.00559 |
| Haiku 4.5 | $0.00012 | $0.00280 |
Grade A, and why
webperf-interaction 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 2d 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 — 240 lines — stays where its author put it; the contents beside it link to each section on GitHub.
WebPerf: Interaction & Animation
JavaScript snippets for measuring web performance in Chrome DevTools. Execute with mcp__chrome-devtools__evaluate_script, capture output with mcp__chrome-devtools__get_console_message.
Scripts
scripts/Forced-Synchronous-Layout.js— Forced Synchronous Layout Detectorscripts/Input-Latency-Breakdown.js— Input Latency Breakdownscripts/Interactions.js— Interactionsscripts/Layout-Shift-Loading-and-Interaction.js— Layout Shift Trackingscripts/Long-Animation-Frames-Helpers.js— LoAF Helpersscripts/Long-Animation-Frames-Script-Attribution.js— Long Animation Frames Script Attributionscripts/Long-Animation-Frames.js— Long Animation Frames (LoAF)scripts/LongTask.js— Long Tasksscripts/Scroll-Performance.js— Scroll Performance Analysis
Common Workflows
Complete Interaction Performance Audit
When the user asks for interaction analysis or "audit responsiveness":
- Interactions.js - List all user interactions with timing
- Input-Latency-Breakdown.js - Break down interaction phases
- Long-Animation-Frames.js - Detect blocking animation frames
- LongTask.js - Identify long tasks blocking the main thread
- Scroll-Performance.js - Measure scroll smoothness
INP Deep Dive
When INP is slow (>200ms) or the user asks "debug INP" or "slow interactions":
- Interactions.js - Identify which interactions are slow
- Input-Latency-Breakdown.js - Break down into input delay, processing time, presentation delay
- Long-Animation-Frames.js - Find animation frames >50ms that block interactions
- Long-Animation-Frames-Script-Attribution.js - Identify scripts causing the blocking
- Long-Animation-Frames-Helpers.js - Get detailed timing and attribution helpers
Scroll Jank Investigation
When the user reports "scroll jank", "choppy scrolling", or "scroll performance issues":
- Scroll-Performance.js - Measure scroll smoothness and frame drops
- Long-Animation-Frames.js - Detect frames causing jank (>50ms)
- Layout-Shift-Loading-and-Interaction.js - Check for layout shifts during scroll
- Long-Animation-Frames-Script-Attribution.js - Find scripts running during scroll
What ships with it
11 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- references/schema.md 20 KB
- references/snippets.md 4.1 KB
- scripts/Forced-Synchronous-Layout.js 3.0 KB runs code
- scripts/Input-Latency-Breakdown.js 1.9 KB runs code
- scripts/Interactions.js 2.0 KB runs code
- scripts/Layout-Shift-Loading-and-Interaction.js 2.8 KB runs code
- scripts/Long-Animation-Frames-Helpers.js 4.6 KB runs code
- scripts/Long-Animation-Frames-Script-Attribution.js 2.9 KB runs code
- scripts/Long-Animation-Frames.js 3.5 KB runs code
- scripts/LongTask.js 2.2 KB runs code
- scripts/Scroll-Performance.js 2.5 KB runs code
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.
- 2d ago First seen · 240 lines · 124 tokens per session scan A d4b831a5dc7f
webperf-interaction is a skill published in the GitHub repository nucliweb/webperf-snippets (1,445 stars, last pushed 1mo ago), licensed MIT. It adds 124 tokens to every session and 2,797 once invoked, about $0.0006 per session on Opus 5. 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 2026-08-30.
Other skills, from other repositories
module_bottleneck
Find slowest PyTorch modules in recent steps.
evalscope
LLM evaluation & inference performance testing via the evalscope CLI. Translates natural language requests into evalscope commands for: (1) Model accuracy evaluation — runs 160+ benchmarks against local checkpoints or API endpoints (OpenAI-compatible, Anthropic, LiteLLM); (2) Performance stress testing — TTFT, TPOT…
hotpath_init
Configure hotpath profiling in a Rust project. Adds the hotpath dependency with feature-gated setup, instruments main with hotpath::main, functions with measure/measureall, and wraps channels, mutexes, rwlocks, streams, futures, reqwest clients, axum routers and byte-level I/O with hotpath macros. Use when the user…
hotpath_bump
Bump the hotpath version number across the workspace and related files. Updates crate versions in Cargo.toml files (exact patch version) and version references in the backend middleware, hotpathinit skill, and README (major.minor only). Use when the user wants to bump, bump the version, or release a new hotpath…
opentelemetry-net-instrumentation
Provides guidance for implementing OpenTelemetry instrumentation in .NET codebases, covering tracing (Activities/Spans), metrics, logs, naming conventions, error handling, performance, SDK setup, resources, context propagation, and API design best practices.
database-performance
Database access patterns for performance. Separate read/write models, avoid N+1 queries, use AsNoTracking, apply row limits, and never do application-side joins. Works with EF Core and Dapper.