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

Annotations indicate readOnly=false and destructiveHint=false, which aligns with the mutation described. The description adds behavioral context (e.g., omit message_id to mark all unread) and mentions a requirement (chat_jid), going beyond annotations without contradiction.

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?

The description is compact and direct, two sentences with no redundant information. It efficiently conveys the operation and key parameters.

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?

The description is sufficient for the tool's simplicity. It covers the operation, required/optional parameters, and bulk behavior. No output schema exists, so return values are not expected. Error handling isn't mentioned, but this is acceptable given the tool's scope.

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 descriptions are absent, but the description explains chat_jid (required), message_id (optional, marks up to), and message_ids (bulk). The 'account' parameter is not explained, so coverage is partial but covers the core semantics.

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?

The description clearly states the action: 'Mark messages as read in a chat.' This is specific and distinguishes from sibling tools like whatsapp_send_text or whatsapp_message_delete.

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 clear usage details: requires chat_jid, optional message_id to mark up to a specific message or omit to mark all unread, and bulk support via message_ids. It doesn't explicitly compare to alternatives but the intent is evident.

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