Instructions for the backend part of a WhatsApp integration that connects through Baileys, stores data in SQLite, and provides tools through MCP.

Building message and contact storage, WhatsApp synchronisation, media downloads, MCP tools, and the controller API used by the GUI.

It gives the backend agent clear ownership and boundaries while it handles WhatsApp connections, storage, tool calls, and communication with the user interface.

How joaohts/whatsapp-mcp configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to joaohts/whatsapp-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/joaohts/whatsapp-mcp/main/.claude/agents/backend.md

Clone the repo

git clone --depth 1 https://github.com/joaohts/whatsapp-mcp

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/agents/joaohts/whatsapp-mcp/backend/github.svg)](https://agentmods.dev/agents/joaohts/whatsapp-mcp/backend)

Your own site

<a href="https://agentmods.dev/agents/joaohts/whatsapp-mcp/backend"><img src="https://agentmods.dev/badge/agents/joaohts/whatsapp-mcp/backend/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/agents/joaohts/whatsapp-mcp/backend"><img src="https://agentmods.dev/badge/agents/joaohts/whatsapp-mcp/backend.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 21 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 754 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found 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.

Model	Per session	Once invoked
Fable 5.1	$0.00021	$0.00754
Opus 5.5	$0.00008	$0.00302
Sonnet 5.5	$0.00004	$0.00151
Haiku 4.5	$0.00002	$0.00075

Measured 2mo ago against content hash 735bc73f53a2, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

backend 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 2mo 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.

.claude/agents/backend.md · 57 lines

How it starts

The opening of the file, as written. The whole thing — 57 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are the backend agent for the WhatsApp MCP project. Your job is to build the Node modules that:

Talk to WhatsApp via Baileys.
Persist chats / messages / contacts / media-refs to SQLite.
Serve MCP tool calls over stdio when launched in --mcp mode.
Expose a controller API for the GUI side to drive pairing / status / sync / config.

Read first

PLANNING.md — the design doc. Treat it as authoritative.
src/types/tools.ts — the MCP tool surface. You implement each tool listed in TOOLS.
src/types/messages.ts — data shapes returned by tools and persisted in SQLite.
src/types/ipc.ts — the BackendController interface you must expose to the GUI.

You own

src/baileys/** — connection lifecycle, event listeners, history fetch, media download.
src/store/** — SQLite schema, migrations, queries, FTS5 over message bodies.
src/mcp/** — MCP server entry (server.ts), tool dispatch, content packaging.
src/backend/** — the BackendController implementation per src/types/ipc.ts.

Do NOT touch

src/renderer/**, src/main/window.ts, src/preload.ts — GUI agent's lane.
electron-builder config in package.json — GUI agent's lane.
PLANNING.md, README.md, LICENSE — design docs / project meta.

Shared / coordinate carefully

src/types/** — both agents read these. If a shape needs changing, update it and call it out clearly in your commit message so the GUI agent rebases cleanly.
src/main/index.ts — entry point that routes to GUI or MCP mode. Leave alone unless the routing itself needs to change.

Working agreement

Branch: backend. Worktree: ~/fun/whatsapp-mcp-backend/.
Commit small + often. Do not push to a remote — origin is not configured yet.
One implementation file per tool: src/mcp/tools/<tool_name>.ts. The dispatcher (src/mcp/server.ts) iterates over TOOLS from src/types/tools.ts.
The read-only contract is enforced by never importing Baileys functions that mutate state (sendMessage, readMessages, sendPresenceUpdate, etc.). If you find yourself needing one, stop and re-read PLANNING.md.
Initial sync blocks tool responses — Claude's first call after launch must wait for the post-pair history sync to land before returning.
Log to ~/Library/Logs/WhatsAppMCP/mcp.log in --mcp mode. Stdout is reserved for the MCP transport.

Read the full file on GitHub · 57 lines

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.

2mo ago First seen · 57 lines · 21 tokens per session scan A 735bc73f53a2

Subscribe to this mod's changes

backend is an agent published in the GitHub repository joaohts/whatsapp-mcp (0 stars, last pushed 5mo ago), licensed MIT. It adds 21 tokens to every session and 754 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Backend and APIs

backend next to 6 agents from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
backendjoaohts/whatsapp-mcp	Agent	0	5mo ago	MIT	A	21	Claude Code
php-developerdavepoon/buildwithclaude	Agent	3.7k	yesterday	MIT	A	51	Claude Code
backend-reviewerjeremylongshore/tons-of-skills-marketplace	Agent	2.9k	yesterday	MIT	A	36	Claude Code
integrations-engineeravelikiy/great_cto	Agent	112	2d ago	MIT	A	106	Claude Code
gatetonone-ai/tonone	Agent	77	23d ago	MIT	A	19	Claude Code
broadcasting-agentSofttor/nestjs-hexagonal	Agent	5	29d ago	MIT	A	58	Claude Code
dotnet-architecture-reviewerStefanTheCode/dotnet-ai-toolkit	Agent	26	2mo ago	MIT	A	102	Claude Code

whatsapp-mcp: Agent for Claude Code