Get an 8-character pairing code for a WhatsApp phone number to link a device without scanning a QR code. Works only while logged out and returns the code.
Get an 8-character pairing code for a phone number, to link it without scanning a QR (WhatsApp, Linked devices, Link with phone number). Only works while logged out. Returns the code.
| Name | Required | Description | Default |
|---|---|---|---|
| phone | Yes | Phone number (7-15 digits) |
Changes observed during successful MCP inspections.
v2.0.0Input schema / properties / phone / descriptionPrevious value: -"Phone number (10-15 digits)"New value: +"Phone number (7-15 digits)"Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations supply readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely non-derivable behavior: the logged-out-only precondition and the fact that it returns the code. It does not cover expiry or failure modes of the code, keeping it below 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single dense sentence front-loads the verb and the precondition-relevant context, with zero filler. Every clause (format, purpose, alternative, precondition, return) earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
With no output schema, the description compensates by stating 'Returns the code.' Combined with annotations carrying the safety profile and the explicit logged-out precondition, an agent has enough to call it correctly. Missing details like code validity window or error behavior keep it from a 5.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100% and there is a single parameter, so the schema already documents 'phone' with its 7-15 digit constraint. The description only restates 'for a phone number' and adds no format or edge-case detail beyond the schema, matching the baseline 3.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb (Get) and resource (8-character pairing code for a phone number) with a concrete format detail. The phrase 'to link it without scanning a QR' distinguishes it from the sibling QR-code tools (whatsapp_get_qr_code / whatsapp_get_qr_code_image) without opening either schema.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Provides the decisive precondition 'Only works while logged out,' which is exactly the kind of when-to-use signal an agent needs. It implies the QR path as the alternative via 'without scanning a QR' but does not name the sibling tool explicitly, so it falls just short of the 5 bar.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.