wacli

A command-line tool for sending WhatsApp messages to other people and searching or synchronizing WhatsApp history.

In plain words
What is it for?
Use it to authenticate, find chats, search messages, sync history, and send text or files to a specified contact or group.
Why use it?
It provides terminal-based access to WhatsApp conversations while requiring the recipient and message to be clear before sending.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/understudy-ai/understudy/wacli
Any agent
npx skills add understudy-ai/understudy --skill wacli
Clone the repo
git clone --depth 1 https://github.com/understudy-ai/understudy

Made for: Claude Code, Codex.

Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 654 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 92% copy Near-identical to another mod 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 $0.00031 $0.00654
Opus 5 $0.00015 $0.00327
Sonnet 5 $0.00006 $0.00131
Haiku 4.5 $0.00003 $0.00065

Measured 2d ago against content hash 4449f8d01e93, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

wacli 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 2d 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.

Origin

This is a copy

92% identical to wacli — 6 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/wacli/SKILL.md · 73 lines

What it actually says

wacli

Use wacli only when the user explicitly asks you to message someone else on WhatsApp or when they ask to sync/search WhatsApp history. Do NOT use wacli for normal user chats; Understudy routes WhatsApp conversations automatically. If the user is chatting with you on WhatsApp, you should not reach for this tool unless they ask you to contact a third party.

Safety

  • Require explicit recipient + message text.
  • Confirm recipient + message before sending.
  • If anything is ambiguous, ask a clarifying question.

Auth + sync

  • wacli auth (QR login + initial sync)
  • wacli sync --follow (continuous sync)
  • wacli doctor

Find chats + messages

  • wacli chats list --limit 20 --query "name or number"
  • wacli messages search "query" --limit 20 --chat <jid>
  • wacli messages search "invoice" --after 2025-01-01 --before 2025-12-31

History backfill

  • wacli history backfill --chat <jid> --requests 2 --count 50

Send

  • Text: wacli send text --to "+14155551212" --message "Hello! Are you free at 3pm?"
  • Group: wacli send text --to "[email protected]" --message "Running 5 min late."
  • File: wacli send file --to "+14155551212" --file /path/agenda.pdf --caption "Agenda"

Notes

  • Store dir: ~/.wacli (override with --store).
  • Use --json for machine-readable output when parsing.
  • Backfill requires your phone online; results are best-effort.
  • WhatsApp CLI is not needed for routine user chats; it’s for messaging other people.
  • JIDs: direct chats look like <number>@s.whatsapp.net; groups look like <id>@g.us (use wacli chats list to find).
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. 2d ago First seen · 73 lines · 31 tokens per session scan A 4449f8d01e93

Subscribe to this mod's changes

wacli is a skill published in the GitHub repository understudy-ai/understudy (456 stars, last pushed 2mo ago), licensed MIT. It adds 31 tokens to every session and 654 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to wacli, differing in 6 lines, and is treated as a copy.