Install String (skill for AI agents)

You are reading this to learn how to install String and call SFMD apps from any shell tool. Follow these steps in order.

1. Install

npm install -g @string-os/string

Requires Node.js 20+. The daemon (stringd) auto-starts on first call — no manual --daemon start needed. Verify:

string --help

2. The output frame

Every string call wraps stdout in:

<𝒞=string:<topic>>
...payload...
</𝒞>

Read the payload between the markers. The opener tells you which topic the call ran in.

3. Call shape

string <topic> '<command>'

A topic is the session label and scopes session state (current document, history, env vars).

Same topic = same state. Reserved hub names cannot be used as free-form labels.

4. Open an app and discover its actions

string app:weather '/open app:weather'

Response starts with the action menu:

[actions] /act.now --city <string> | /act.forecast --city <string> | /act.search --q <string>
          /act.<name> --help for details

That line is your discovery output — every action the app exposes, with its required flag types. Inside an app: topic, /open with no argument re-opens the app's home.

5. Run an action

string app:weather '/act.now --city Seoul'
# Positional (declaration order):
string app:weather '/act.now Seoul'
# Short alias if defined:
string app:weather '/act.now -c Seoul'
# Multi-word values — quote or use +:
string app:weather '/act.now "New York"'
string app:weather '/act.now New+York'
# Field schema:
string app:weather '/act.now --help'

Successful output:

<𝒞=string:app:weather>
seoul: Sunny +20°C ↘6km/h
</𝒞>

6. Install a new app

From the cookbook (canonical example collection):

git clone https://github.com/string-os/cookbook.git
cd cookbook
string setup '/install --app ./apps/weather/string.md'

From any URL:

string setup '/install --app https://example.com/my-app/string.md'

The runtime copies the file into ~/.string/users/default/packages/<name>/ and registers it. From this point on, app:<name> resolves from any session.

Available apps in the cookbook:

7. Set credentials

Apps that need API keys declare requires: [VAR_NAME] in frontmatter. When you /open an app without the var set, the response begins with:

[!] Missing required env: $MOLTBOOK_API_KEY
    Set: /set $MOLTBOOK_API_KEY = "..."
    Setup: /open requirements.md

Set the var with /set (persists to disk in the current topic's scope):

string app:moltbook '/set $MOLTBOOK_API_KEY = "moltbook_xxx"'

Resolution cascades: config → app → global. A var set globally is visible to every app unless overridden at a more specific scope.

Shell-exported export VAR=... also works as a fallback (the daemon reads process.env), but /set is preferred — survives daemon restarts and keeps secrets out of shell history.

8. Handle action errors

When an action fails and the app has a requirements.md, the error gets a trailing hint:

ERROR(EXIT_127): kubectl: command not found

Setup info: /open requirements.md

When you see that, run string app:<name> '/open requirements.md' to see what to install or configure. Then retry the action.

Reference

More

• Documentation
• Cookbook (example apps + walkthroughs)
• Source