What you can use in app YAML

This page is the inventory for app authors. Everything below is something you declare or call from app.yaml (and optional bundle files). Copy examples from the tutorials and paste them into your own app.

Modules you can enable

Declare them under tools.modules:

Module	Tools (actions)	Typical use
bash	run	Shell commands
browser	open, act, read	Browser automation
database	connect, query, disconnect	SQL / data stores
filesystem	read, write, edit, multi_edit, glob, grep, delete	Files in the workdir
http	request, download, upload	HTTP calls
lsp	diagnostics, notify_change	Language-server feedback
mcp	Virtual tools from MCP servers	External tool servers
pieces	Dynamic (installed pieces)	Digitorn pieces
preview	inspect, snapshot	Live preview pane
previewshot	screenshot	Preview screenshots
rag	Search / ingest family (see rag)	Knowledge bases
scheduler	schedule	Timed wake-ups
web	search, fetch	Web search and fetch
workspace	baseline, changes, diff, history, approve, approve_hunks, reject, reject_hunks, commit, revert, revert_commit, log	Git-style revise / approve

Also available without a full module page in every tutorial:

Id	Role in YAML
memory	Goals, remember, tasks
context_builder	Meta-tools (discovery, parallel, background)
agent_spawn	Multi-agent agent (and kv when spawn is on)
channels	Background I/O adapters (webhook, cron, …)

Built-in meta tools

When discovery / context injection is on, agents can use tools such as:

search_tools, get_tool, execute_tool, run_parallel, background_run (including watch loops), and when enabled ask_user, call_app, use_skill, memory helpers, agent, kv.

Details: Built-in tools, Primitives.

Do not invent these

Older docs sometimes listed names that are not valid in today's app YAML:

Avoid	Use instead
web_preview / dev_tools modules	preview / previewshot + ui.workspace
watch_start family	background_run with watch: true
http.get / http.post	http.request
bash as an action name	bash.run (actions: [run])
mcp.call_tool / mcp.list_tools grants	grant: [{ module: mcp }] (virtual tools at runtime)
channels.send_message tools	Channel adapters + app mode, not catalog tools
workspace write/read/edit	File I/O is filesystem.*

Channels you can declare

Under tools.channels, adapters such as webhook, cron, rss, telegram, discord, whatsapp, pieces, and primitives are the supported shapes. See Channels.

Next steps

• Start writing: Getting started
• Full grammar: Language
• Per-module pages: Module reference