Pin or unpin a chat at the top of the WhatsApp chat list for this account. Use it to keep important conversations visible; returns a success confirmation.
Pin a chat to the top of the chat list, or unpin it. Only affects this account. To pin a message inside a chat, use whatsapp_pin_message. Returns a success confirmation.
| Name | Required | Description | Default |
|---|---|---|---|
| chatId | Yes | Chat JID | |
| pinned | Yes | Pin or unpin |
Changes observed during successful MCP inspections.
v2.0.0Input schema / properties / chatId / descriptionPrevious value: -"Chat ID"New value: +"Chat JID"Input schema / properties / pinned / descriptionPrevious value: -"Whether to pin or unpin"New value: +"Pin or unpin"Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare mutation (readOnlyHint=false), idempotence, and non-destructiveness, so the bar is lower. The description adds useful behavioral context beyond annotations: it scopes the effect to 'this account' and states that it 'Returns a success confirmation,' which tells the agent what to expect from the call. It does not cover permissions or rate limits, but those are minor for this simple operation.
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?
Three short sentences with zero waste. The primary action is front-loaded, the scope and alternative follow immediately, and the return behavior closes efficiently.
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?
For a simple two-parameter toggle with rich annotations and no output schema, the description is complete. It covers the action, the account scope, the key alternative tool, and the response shape, leaving no meaningful gap for an agent to call it correctly.
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%, so the schema already fully documents both parameters ('Chat JID' and 'Pin or unpin'). The description adds no syntax, format, or edge-case detail beyond what is already in the schema, so the baseline of 3 applies.
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 and resource ('pin a chat to the top of the chat list, or unpin it') and explicitly distinguishes itself from the sibling whatsapp_pin_message by naming it and explaining the difference. An agent can tell exactly what this tool does and what it does not.
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 an explicit alternative for the most likely confusion: 'To pin a message inside a chat, use whatsapp_pin_message.' It also clarifies the scope of the effect ('Only affects this account'), so the agent knows when this tool is appropriate versus its message-level sibling.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.