Install the custom-actions skill

A skill is a Markdown instruction file a coding agent loads when a task matches it. Install superdoc-custom-actions when someone on the project will extend the action surface, so the agent writes an action that fits the SDK instead of inventing a shape around it.

Skills and MCP solve different problems. The MCP server lets an agent edit DOCX files directly through tools. A skill teaches an agent how to write application code against @superdoc/sdk or superdoc-sdk. A project that does both installs both.

Install

The skill lives in the open-source repository rather than inside the npm package, so it is installed from there with the skills CLI. Run this from your application's root directory:

npx skills add superdoc/docx-editor/packages/sdk/skills/superdoc-custom-actions --copy

--copy vendors the skill into your project so it is committed alongside your code. Add -a <agent> to install it for one supported coding agent instead of all of them.

Then ask for the operation you need:

Add a custom action that inserts a footnote after a piece of text.

What it carries

The skill encodes the parts of the workflow an agent gets wrong unprompted:

• Choose the tier deliberately, and stay with steps when the built-in actions already express the operation.
• Namespace the action as superdoc.<verb> so it cannot collide with a built-in.
• Take arguments a model can actually produce, such as anchor text or an ordinal, and resolve low-level targets inside the action.
• Make a Python run action async def when the host drives an async client, because a synchronous body receives un-awaited coroutines.

It also carries verification discipline. The agent is told to validate every operation against the contract, then run the action against a real document and confirm the change independently rather than trusting a receipt. When no document is available it must label the result a draft. That rule is why the skill is worth installing rather than describing: an agent that cannot verify will otherwise present unverified work as finished.

Worked example packs ship next to the skill file, in both JavaScript and Python.

Keep it current

--copy vendors the file, so it does not update itself. The skill describes an API surface that changes between releases, so re-run the install as part of the change that bumps the SDK. Otherwise the agent follows instructions for a version you no longer run.

Next

Custom actions is the reference this skill teaches. For agents that should edit documents rather than write code, connect the MCP server.