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

Annotations already indicate readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context: the link expires after 60 seconds and a new one must be requested. This is beyond what annotations provide. It does not mention authentication requirements or rate limits, but for a read-only operation with these annotations, the disclosure is adequate.

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 two sentences with no redundancy. The primary purpose is front-loaded, and the expiry note is concise and actionable. Every word earns its place, making it highly efficient for an agent to parse.

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 tool with a single parameter, an output schema present, and read-only annotations, the description covers the essential behavior (link retrieval and expiry) and usage context (source of message). Nothing critical is missing for an agent to invoke it correctly. The output schema likely describes the return format, so no need to duplicate that here.

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 0%, so the description must compensate. The description implies that messageId is the ID of the WhatsApp document message returned by get_whatsapp_conversation, but it does not explicitly define the parameter or explain its format. While the connection is inferable, the description does not directly elaborate on messageId, leaving some ambiguity. This is a moderate gap given the lack of schema descriptions.

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 (get a secure download link), the resource (WhatsApp document message), and the source (returned by get_whatsapp_conversation). This unambiguously differentiates it from other tools like send_whatsapp_message or get_whatsapp_conversation itself. The verb-resource pairing is specific and unambiguous.

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?

The description specifies that this tool is for document messages returned by get_whatsapp_conversation, giving clear context on when to use it. It also provides practical guidance on handling link expiry ('request a new one if it expires'). However, it does not explicitly mention when not to use it, but since no alternative download tool exists among siblings, this is acceptable.

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