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

Annotations indicate readOnlyHint=false, idempotentHint=false, and destructiveHint=false, but the description adds key behavioral context: the QR code expires every ~20 seconds and the need to poll for status. This goes beyond the annotations and informs the agent of the time-sensitive nature of the 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?

The description is two sentences with no redundant information. The purpose is front-loaded, followed by the return format and the immediate next step. Every clause serves a purpose, making it highly efficient.

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?

Given the tool has no parameters and the output schema exists (though not shown), the description is complete. It covers what the tool does, what it returns (QR code), the expiry behavior, and how to proceed. An agent has everything needed to invoke 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?

With zero parameters and full schema coverage (100%), the baseline is 4. The description adds value by mentioning the return of a QR code and the pair_id, which is critical for the next step (polling). This enriches the agent's understanding of the tool's output even though the schema is empty.

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 states a clear verb+resource: 'Begin linking a new WhatsApp account.' It distinguishes itself from sibling tools like wa_pair_status (polling) and wa_unpair_account (unlinking) by specifying it initiates the pairing process and returns a QR code.

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 explicitly instructs the agent to poll wa_pair_status with the returned pair_id, establishing a clear usage sequence. It also notes the code expires every ~20 seconds, which implies the need for polling. This provides concrete guidance on how to use the tool correctly.

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