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

With no annotations provided, the description carries the full burden. It discloses the core behavior (sends a one-time code) and a prerequisite (via a connected device), which is helpful. Yet it omits details about session handling, potential side effects, or how the session links to otp_verify, leaving room for uncertainty.

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 a single, front-loaded sentence that communicates the action, target, and prerequisite without redundancy. Every word contributes value.

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 selecting the tool, but it does not mention how the session ID or code is returned, nor does it note the complementary otp_verify tool for completing the flow. With no output schema or annotations, this leaves a gap for an agent needing to chain tools.

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?

The input schema describes all five parameters with 100% coverage, so the baseline is 3. The description does not add any parameter-specific meaning beyond that already in the schema, but it does not need to.

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 tool starts a LoginWA OTP session by sending a one-time code to a WhatsApp phone number. It specifies the action (send), the resource (WhatsApp number), and the context (OTP session), effectively distinguishing it from siblings like otp_verify and send_message.

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 usage is implied by the OTP-specific wording and the mention of 'LoginWA OTP session,' making it clear when to use this tool. However, there are no explicit alternatives or exclusions mentioned, so the agent must infer the boundary against other messaging tools.

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