Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add f-labs-io/agent-html-skills/plugin install html-skillsWrote 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/skills/f-labs-io/agent-html-skills/html-erd-explorer)<a href="https://agentmods.dev/skills/f-labs-io/agent-html-skills/html-erd-explorer"><img src="https://agentmods.dev/badge/skills/f-labs-io/agent-html-skills/html-erd-explorer/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/f-labs-io/agent-html-skills/html-erd-explorer"><img src="https://agentmods.dev/badge/skills/f-labs-io/agent-html-skills/html-erd-explorer.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00097 | $0.02097 |
| Opus 5 | $0.00048 | $0.01048 |
| Sonnet 5 | $0.00019 | $0.00419 |
| Haiku 4.5 | $0.00010 | $0.00210 |
Grade A, and why
html-erd-explorer 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 5d 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 — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.
HTML ERD & Schema Explorer
Database schemas are inherently visual — tables connected by foreign keys, with cardinality and direction. ERDs in markdown are awkward; in dedicated tools they're heavy. An HTML ERD is portable, embeddable in a doc, and click-to-explore.
Pre-flight — run BEFORE writing the artifact
Invoke html-skills:html-skills-listen (Skill tool) first; it is idempotent. If it returns a URL, inject it verbatim as window.__CLAUDE_SUBMIT_URL__ in the HTML you are about to write, ?t= query string included (a local, single-session loopback handshake — not a credential). If it reported web/sandbox mode, leave that line out; submitToClaude then falls back to clipboard mode.
When to use this skill
- "Diagram our [schema, data model, database, tables]"
- "Show me how [table X] relates to [table Y]"
- "Document the schema for [feature/service]"
- "Plan the migration from this schema to that one"
- "Explain how a query touches the schema"
- Any time a database structure with ≥3 tables enters the conversation
Output requirements
Tables rendered as cards/boxes with their columns listed. Foreign key relationships drawn as connecting lines with cardinality markers (1, *, etc.). Click a table to expand or focus.
Include a legend explaining symbols (PK, FK, indices, nullable).
Core ERD components
Table card
┌─────────────────────────────┐
│ users │
├─────────────────────────────┤
│ 🔑 id uuid │
│ email text unique │
│ created_at timestamptz │
│ org_id uuid → orgs │
└─────────────────────────────┘
Each card shows:
- Table name (header)
- Columns: name, type, key markers (PK/FK), nullability, indices
- Optional: row count estimate, table-level comments
Relationship lines
- Solid line = foreign key
- Cardinality markers at each end (1, , 0..1, 1..)
- Crow's-foot notation preferred over text labels for cardinality
- Color or style to distinguish strong (cascading) from weak (set null) relationships
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.
- 5d ago Changed · +12 lines 41a898655b41
- 9d ago First seen · 138 lines · 97 tokens per session scan A cc23bd171f6b
html-erd-explorer is a skill published in the GitHub repository f-labs-io/agent-html-skills (55 stars, last pushed 7d ago), licensed MIT. It adds 97 tokens to every session and 2,097 once invoked, about $0.0005 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.
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