custom-js

custom-js is a skill for Claude Code, Codex from withoneai/one-agent-plugin. It costs 128 tokens per session (1,405 once invoked), scanned A, original, MIT.

An automation service that runs JavaScript and provides tools for PDFs, screenshots, forms, static websites, web scraping, and email-triggered webhooks. A webhook is a URL that receives data automatically from another service.

In plain words
What is it for?
Use it to execute JavaScript, generate PDFs or screenshots, scrape websites, host static files, process forms, and connect email events to workflows.
Why use it?
It lets no-code and AI workflows run custom code or handle web tasks that built-in steps cannot cover. It brings several backend utilities together through automation tools and HTTP APIs.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to execute JavaScript, generate PDFs or screenshots, scrape websites, host static files, process forms, and connect email events to workflows.

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Install with agentmods
npx agentmods add skills/withoneai/one-agent-plugin/custom-js
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.

Any agent
npx skills add withoneai/one-agent-plugin --skill custom-js
Clone the repo
git clone --depth 1 https://github.com/withoneai/one-agent-plugin

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for custom-js

README.md
[![agentmods](https://agentmods.dev/badge/skills/withoneai/one-agent-plugin/custom-js/github.svg)](https://agentmods.dev/skills/withoneai/one-agent-plugin/custom-js)
Your own site
<a href="https://agentmods.dev/skills/withoneai/one-agent-plugin/custom-js"><img src="https://agentmods.dev/badge/skills/withoneai/one-agent-plugin/custom-js/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.

agentmods 80×15 button for custom-js

Your own site · 80×15
<a href="https://agentmods.dev/skills/withoneai/one-agent-plugin/custom-js"><img src="https://agentmods.dev/badge/skills/withoneai/one-agent-plugin/custom-js.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 128 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,405 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00128 $0.01405
Opus 5 $0.00064 $0.00702
Sonnet 5 $0.00026 $0.00281
Haiku 4.5 $0.00013 $0.00140

Measured 5d ago against content hash 57fff839c573, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

custom-js 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.

platforms/one-custom-js/skills/custom-js/SKILL.md · 100 lines

How it starts

The opening of the file, as written. The whole thing — 100 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CustomJS through One

CustomJS is an automation platform that provides JavaScript execution, PDF generation, screenshots, forms, static hosting, web scraping, and email-to-webhook tools through Make.com, n8n, and HTTP APIs, allowing teams to add custom logic and backend capabilities to no-code and AI workflows.

One exposes CustomJS through four MCP tools. The table below carries real action ids from One's knowledge base, so for a common operation you can skip search and go straight to reading the action's parameters.

How to run an action

  1. Find the action in the table below, or call search_one_platform_actions with platform custom-js if it is not listed.
  2. Call get_one_action_knowledge with the action id. Do this every time, including for actions in this table. The table gives you the id, not the parameters.
  3. Call execute_one_action with parameters copied from that knowledge.

Never guess a parameter name, a body field, or an enum value. The knowledge has the real schema, and a guessed field is either a 400 or a silent write of the wrong thing.

Before you start

Call list_one_integrations once and confirm CustomJS is connected. If it is missing, the user has not connected it: say so and point them at https://app.withone.ai rather than reaching for raw HTTP.

Each connection carries an access field. If it reports {"policy": "methods", "methods": ["GET"]} the agent is read-only here, so plan a read-only answer instead of attempting a write that will be refused.

Before a write

Creates, updates, deletes and sends land on a real CustomJS account and cannot be recalled. State the action and the specific target in one line before the first write in a task, and let the user stop you. Reads need no confirmation.

Actions

HtmlToPdf

Action Method Path Action id
HTML to PDF POST /html2pdf conn_mod_def::GMa2rhUxtCA::Wr-gQASvQHayBM4mtt5UEw
Test Connection POST /html2pdf conn_mod_def::GMa0rTyROug::z4_htVW6S7-uhd--tr2c-A

Read the full file on GitHub · 100 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. 5d ago First seen · 100 lines · 0 tokens per session scan A 57fff839c573

Subscribe to this mod's changes

custom-js is a skill published in the GitHub repository withoneai/one-agent-plugin (1 stars, last pushed 20d ago), licensed MIT. It adds 128 tokens to every session and 1,405 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 2026-09-03.

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