html-effectiveness

html-effectiveness is a skill for Claude Code, Codex from tincopper/neeko. It costs 142 tokens per session (3,070 once invoked), scanned A, original, Apache-2.0.

Guidance for producing a single interactive HTML document when information is easier to explore visually, such as comparisons, timelines, tables, diagrams, or code reviews.

In plain words
What is it for?
Creating dependency-free browser documents with filters, sortable tables, collapsible sections, diagrams, or annotated changes.
Why use it?
It helps readers scan and interact with complex information instead of reading a long block of Markdown.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/tincopper/neeko/html-effectiveness
Any agent
npx skills add tincopper/neeko --skill html-effectiveness
Clone the repo
git clone --depth 1 https://github.com/tincopper/neeko

Made for: Claude Code, Codex.

Per session 142 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,070 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00142 $0.03070
Opus 5 $0.00071 $0.01535
Sonnet 5 $0.00028 $0.00614
Haiku 4.5 $0.00014 $0.00307

Measured 3d ago against content hash 8743eb39a1e6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

html-effectiveness 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 3d 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.

.agents/skills/html-effectiveness/SKILL.md · 315 lines

How it starts

The opening of the file, as written. The whole thing — 315 lines — stays where its author put it; the contents beside it link to each section on GitHub.

HTML Effectiveness: Interactive Output Engine

Core Principle

Markdown is a wall of text. HTML is a spatial, interactive document.

When you have multi-dimensional information to present, generate a single self-contained HTML file that users can explore, filter, compare, and interact with. The browser is the universal runtime - no build steps, no dependencies, no exports needed.

When to Use This Skill

Use HTML output when ANY of these are true:

  • Comparing 2+ options with trade-offs (side-by-side cards)
  • Presenting data with >5 rows (sortable/filterable table)
  • Showing a timeline or sequence of events
  • Explaining a concept with collapsible sections
  • Reviewing code changes (annotated diffs)
  • Presenting a plan with phases and dependencies
  • Showing architecture or system design (boxes + arrows)
  • Any output where the reader needs to SCAN, not read linearly
  • Any output where the reader needs to CHOOSE between options
  • Any output with tabular data, charts, or visual relationships

Use plain markdown when:

  • Simple Q&A (one paragraph answer)
  • Inline code fixes
  • Brief status updates
  • Sequential instructions (do X, then Y, then Z)

9 Output Patterns

Select the pattern that matches your information type:

1. Comparison Board

When: Evaluating approaches, tools, libraries, strategies Structure: Side-by-side cards with clear trade-offs, rating badges, recommendation highlight Interaction: Hover to highlight, click to expand details

2. Annotated Timeline

When: Incident post-mortems, project plans, history, implementation phases Structure: Vertical timeline with colored nodes, expandable details per step Interaction: Click nodes to expand/collapse, filter by category

3. Interactive Report

When: Status updates, analysis results, research findings Structure: Header stats, filterable sections, charts via inline SVG Interaction: Category filters, collapsible deep-dives, search

4. Code Review Board

When: PR reviews, refactoring proposals, architecture changes Structure: File-by-file cards with severity tags, before/after diffs, inline comments Interaction: Filter by severity, expand file details, toggle diff view

Read the full file on GitHub · 315 lines

Changes

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.

  1. 3d ago First seen · 315 lines · 142 tokens per session scan A 8743eb39a1e6

Subscribe to this mod's changes

html-effectiveness is a skill published in the GitHub repository tincopper/neeko (10 stars, last pushed 5d ago), licensed Apache-2.0. It adds 142 tokens to every session and 3,070 once invoked, about $0.0007 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 2026-08-31.

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