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/bearlike/assistant/st-widget-buildernpx skills add bearlike/Assistant --skill st-widget-buildergit clone --depth 1 https://github.com/bearlike/AssistantWhat 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 | $0.00065 | $0.00813 |
| Opus 5 | $0.00032 | $0.00407 |
| Sonnet 5 | $0.00013 | $0.00163 |
| Haiku 4.5 | $0.00006 | $0.00081 |
Grade A, and why
st-widget-builder 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 — 71 lines — stays where its author put it; the contents beside it link to each section on GitHub.
st-widget-builder
st-widget-builder is a sub-agent — delegate to it via spawn_agent. Do not write widgets yourself.
For a static, no-code panel, read generative-ui; use this skill when the result needs code or interactivity.
How to invoke
spawn_agent(
agent_type="st-widget-builder",
task="<data hand-off + purpose — see rules below>",
acceptance_criteria="widget_ready event emitted with app.py and data.json"
)
What goes in the task
The sub-agent has a component catalog and designs the layout itself. Your task must contain only two things:
- Purpose — one sentence: what does the user want to see?
- Data — the file path + field names the widget needs.
# ✓ Correct — data + purpose only
task=(
"Show the current AAPL stock price and recent price trend. "
"Data: /tmp/mewbo/aapl_data.json — fields: quote.price, quote.change, "
"quote.pct_change, quote.open, quote.high, quote.low, quote.volume, "
"daily[].date, daily[].close (30 days, newest first)."
)
# ✗ Wrong — prescribing layout (forces sub-agent away from its catalog)
task=(
"Build a header card with the price in large text, then a row of 5 "
"metric cards, then a green line chart titled '30-Day Price History'. "
"Use a dark theme with Altair."
)
Do not describe layout, sections, component types, chart axes, colors, or themes. The sub-agent's catalog (StockTickerCard, GitHubRepoCard, SearchResultCard, PlantUMLCard, …) already handles these consistently. Prescribing layout bypasses the catalog and forces custom code that looks worse.
Data hand-off
Write structured data to a file before spawning — never paste raw JSON into the task string. Stage it under /tmp/mewbo/ (or the session cwd): the file tools can only read inside /tmp/mewbo/, the cwd, and configured project roots, so a bare /tmp/... path would be unreadable by the sub-agent.
gh search repos --json name,description,stargazerCount,language,url \
--limit 10 "topic:streamlit" > /tmp/mewbo/gh_results.json
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 · 71 lines · 65 tokens per session scan A 67e88014c413
st-widget-builder is a skill published in the GitHub repository bearlike/Assistant (41 stars, last pushed 8d ago), licensed MIT. It adds 65 tokens to every session and 813 once invoked, about $0.0003 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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