whatsapp-mcp-server: Instructions file for Claude Code

CLAUDE.md

whatsapp-mcp-server CLAUDE.md is an instructions file for Claude Code from HalemoGPA/whatsapp-mcp-server. It costs 2,392 tokens per session, scanned A, original, MIT.

Repository instructions for a WhatsApp MCP server, a service that lets an AI assistant work with WhatsApp data. They stress checking the actual network data instead of assuming the app’s display or comments describe the truth.

In plain words
What is it for?
Use it when changing or debugging WhatsApp message parsing, media handling, view-once behavior, deletion, polls, forwarding labels, or resource limits.
Why use it?
WhatsApp’s client application can visually enforce rules that its servers do not, and old comments or documentation may be outdated. These instructions help prevent incorrect conclusions when handling messages and media.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md.

This is HalemoGPA/whatsapp-mcp-server's own configuration. It tells Claude Code how to work on whatsapp-mcp-server itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything whatsapp-mcp-server configures →

Reuse

Borrowing it

Nothing to install: this file belongs to HalemoGPA/whatsapp-mcp-server. 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/HalemoGPA/whatsapp-mcp-server/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/HalemoGPA/whatsapp-mcp-server

Made for: Claude Code.

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Per session 2,392 This file is loaded in full into every session.
When invoked 2,392 The same file — it is already loaded in full.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.02392 $0.02392
Opus 5 $0.01196 $0.01196
Sonnet 5 $0.00478 $0.00478
Haiku 4.5 $0.00239 $0.00239

Measured 8d ago against content hash 6d4b8947881d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

whatsapp-mcp-server CLAUDE.md 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 8d 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.md · 152 lines

How it starts

The opening of the file, as written. The whole thing — 152 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Working on this repo

Read this before changing anything. It is short on purpose.

The one idea

WhatsApp enforces almost everything client-side. The display is not the truth.

"View once", "delete for everyone", poll selection caps, forwarding labels - these are conventions maintained by the app's UI, not guarantees enforced by WhatsApp's servers. The app bets that what people see IS reality, and for almost everyone that bet is correct. It is not correct for us: we read the wire.

The practical consequence, which cost a full day on 2026-07-16:

A rendering is evidence of what a client chose to draw. Nothing more.

Every wrong conclusion that day came from trusting something that renders:

Trusted Said Truth
WhatsApp Desktop "only once - view from your phone" The message was NOT view-once. Desktop reads the envelope; mobile enforces the inner viewOnce flag, which was unset. Fake view-once for weeks.
A code comment "media bytes are downloadable regardless of view count" True when written (Aug 2024), false since Meta's server-side fix (~Nov 2024). Repeated as fact without checking.
whatsmeow's docs selectableOptionCount is "the maximum number of selections" No client enforces N>1. Library docs describe the field's intent, not client behaviour.
Our own docstring "single-select polls will ignore extras" They do not. 3 options on a cap-2 poll register all 3.
A poll tally in the app option counts Five phones showed five different tallies (1/3/3 vs 2/3/2) while the wire said 5/5/5.

The wire never lied. Every single time, the fix was to go look at the actual protobuf, the actual stanza, or run an actual test.

Rules that follow from it

  1. Cite the wire, the proto field number, or a test you ran. Not a doc, not a comment, not a screenshot. If you cannot, say "unverified" and mean it.
  2. A proto field existing does not mean it works. The server may reject it and the recipient's client may ignore it. Those are three different claims. Keep them separate. See docs/protocol-vs-app.md.
  3. Never repeat a comment in this repo as fact. They rot. The two most confidently wrong statements of 2026-07-16 were both comments in this codebase that had been true when written.
  4. Do not claim it works until you have watched it work. "Compiles", "deployed", and "the endpoint returned success" are not "works". A poll vote returned Vote cast while the tally silently stayed at 0.
  5. Phone-origin bugs are invisible to MCP-side testing. Sending through our own API exercises code that hashes/wraps locally and never decrypts or normalises. Two real bugs (all six poll-creation variants; LID-vs-PN on votes) were found within minutes by the user's phone after our own tests passed clean. Close the loop with a real phone before claiming a receive path works.
  6. When the user's observation contradicts your model, they are probably right. "MacBook says only once, phone views forever" was reported three times and explained away twice before it was recognised as the bug it was. The user can see the one surface we cannot.

Read the full file on GitHub · 152 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.

  1. 8d ago First seen · 152 lines · 2,392 tokens per session scan A 6d4b8947881d

Subscribe to this mod's changes

whatsapp-mcp-server CLAUDE.md is an instructions file published in the GitHub repository HalemoGPA/whatsapp-mcp-server (5 stars, last pushed yesterday), licensed MIT. It adds 2,392 tokens to every session, about $0.0120 per session on Opus 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.

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