WhatsMCP: MCP for WhatsApp

Block or Unblock Contact

wa_block_contact

Block a contact on one of your WhatsApp accounts, so they can no longer call or message it — or set unblock=true to unblock one. Reports who it acted on: their number, the name this account's address book has for them, and the country the number belongs to.

Input Schema

TableJSON Schema

Name	Required	Description
`jid`	Yes	the contact — a phone number in international form or a full JID
`unblock`	No	true to unblock a previously blocked contact instead
`account_id`	Yes	the account, as returned by wa_list_accounts

Output Schema

TableJSON Schema

Name	Required	Description
`status`	Yes	ok (the operation succeeded) or refused (nothing was done)
`blocked`	No	every contact on the account's blocklist (wa_list_blocked only)
`contact`	No	the contact that was blocked or unblocked (wa_block_contact only)
`refusal`	No	present only when status is refused

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedSep 22, 2026

changedInput schema / properties / jid / description

Previous value: -"the contact to block — a phone number in international form or a full JID"New value: +"the contact — a phone number in international form or a full JID"

addedInput schema / properties / unblock

Added value: +{
+  "description": "true to unblock a previously blocked contact instead",
+  "type": "boolean"
+}

changedOutput schema / properties / contact / description

Previous value: -"the contact that was blocked or unblocked (wa_block_contact and wa_unblock_contact only)"New value: +"the contact that was blocked or unblocked (wa_block_contact only)"

First observedSep 17, 2026

TDQS

A4.3/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With annotations already indicating a non-read-only, non-destructive operation, the description adds the behavioral effect (prevents calls/messages), the reversibility via unblock=true, and the confirmation output (number, address-book name, country). It goes beyond the schema, though it doesn't discuss repeated-block behavior or idempotency.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight sentences carry the main action, the unblock exception, and the reported outcome with no filler. The most important details are front-loaded, and there is no repetition of schema boilerplate.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 3-parameter tool with full schema coverage, annotations, and an output schema, the description sufficiently covers scope, the optional unblock behavior, and what the operation reports. No essential call information is missing; account_id linkage is handled in the schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all three parameters. The description mostly restates the same semantics for jid and unblock, adding only the natural-language context about what the result reports. This matches the baseline for fully covered schemas.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a concrete action: block a contact on a specific WhatsApp account, with the unblock path explicitly encoded via unblock=true. It also names the effect ('can no longer call or message it') and the resource ('one of your WhatsApp accounts'), making the tool's purpose unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear invocation context: block when you want to stop a contact from calling or messaging, and set unblock=true to reverse a previous block. It doesn't explicitly name sibling alternatives or exclusions, but the dual-mode guidance is sufficient for correct selection and use.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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