MicroFn CLI Skill

Use this skill when interacting with the MicroFn platform through the installed CLI commands (microfn or mfn).

What MicroFn is

MicroFn is a cloud platform for sandboxed JavaScript functions. Use it to run focused JavaScript snippets as deployed functions. Functions can power app behavior and can also be enabled as tools for agent workflows.

Install and authenticate

1. Install globally with npm install -g microfn.
2. Use either command: microfn or mfn.
3. Create an API key at https://microfn.dev/users/settings/api.
4. Pass auth with --token mfn_xxx or MICROFN_API_TOKEN.

Core workflows

List functions

Run microfn list (or mfn list) to inspect available functions.

Deploy a new function

1. From file: microfn create <name> <path-to-file>.
2. From stdin: cat file.ts | microfn create <name> -.

Update function code

1. From file: microfn push <owner/name> <path-to-file>.
2. From stdin: cat file.ts | microfn push <owner/name> -.

Inspect function details

Use:

• microfn info <owner/name>
• microfn code <owner/name>

Execute a function

1. Inline payload: microfn execute <owner/name> '{"key":"value"}'.
2. Stdin payload: echo '{"key":"value"}' | microfn execute <owner/name> -.
3. Include logs when needed: add --include-logs.

Work with tool-enabled functions

1. Check microfn info <owner/name> for MCP tool status.
2. Keep function signatures stable when functions are consumed as tools.

Function source contract (important)

When writing code for create or push, follow the CLI contract used in command help:

1. Export exactly one entrypoint function style.
2. Prefer export async function main(input) { ... }.
3. If main is not exported, export exactly one named function; it will be auto-wrapped as main().
4. The function should accept the execution input object and return a JSON-serializable value.
5. Sync and async functions are both valid.
6. Use default imports for @microfn/* packages.
7. Do not use named imports for @microfn/*.

Valid examples:

export async function main(input) {
  const { name = "world" } = input || {};
  return { greeting: `hello ${name}` };
}

export async function greet(payload) {
  return { greeting: `hello ${payload?.name || "world"}` };
}

import kv from "@microfn/kv";
import secret from "@microfn/secret";

export async function main() {
  const apiKey = await secret.get("API_KEY");
  const count = (await kv.get("count")) || 0;
  await kv.set("count", count + 1);
  return { apiKeyPresent: !!apiKey, count: count + 1 };
}

Invalid import pattern:

import { kv } from "@microfn/kv";

Output and troubleshooting

1. Use --output json for scriptable output.
2. Use --debug for verbose request/response diagnostics.

Delivery checklist

1. Show examples with microfn (note mfn is equivalent).
2. Keep command examples reproducible and copy-paste ready.
3. Preserve the product model: sandboxed JavaScript functions that can also be used as tools.