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

Annotations include destructiveHint=true, and the description adds useful context about token scope and the upgrade path, which goes beyond annotations. It does not explain the destructive nature (e.g., OTP invalidation), but since the annotation already flags it and the description provides flow context, it's good value.

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 three short sentences, each adding critical information: what it does, prerequisite, and next step. No wasted words; front-loaded with the main purpose.

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?

There is an output schema, so return values are covered. The description covers prerequisites, token scope, and next step, making it context-rich. It doesn't discuss failure modes or rate limits, but given the presence of structured data, this is acceptable.

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 coverage is 100%, so the baseline is 3. The description adds meaning by clarifying that session_id comes from auth_start and that no email is needed, plus the code is 6-digit and from email. This enriches the parameter understanding beyond the schema.

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 verifies a 6-digit OTP code and returns a guest-scope bearer token for specific downstream tools. This distinguishes it from siblings like auth_start, auth_check_payment, and auth_resend_otp by specifying the exact action and output.

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 provides explicit context: requires session_id from auth_start, explicitly says no email needed, and directs when to call auth_check_payment after checkout/payment. This gives clear when-to-use and next-step guidance, even if it doesn't mention auth_resend_otp explicitly.

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