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

With no annotations, the description carries the full burden. It discloses the success condition ('if the code is correct') and the authentication requirement, but doesn't mention failure behavior, response format, or whether the code becomes invalid after use. This is a moderate gap for a mutation-like verification tool.

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 concise and front-loaded with the core action, followed by an essential access note. Each sentence serves a purpose—action and authentication context—with no redundant wording. It's appropriately sized for the tool's simplicity.

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 explains the flow and authentication but omits details about the response (no output schema) and failure behavior. Since there's no output schema, the agent has no expectation of return values. It also doesn't explicitly state that a prior start_add_email call is required, though it's implied by 'add-email flow'. These gaps make it only moderately complete for a two-parameter verification tool.

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 both parameters have descriptions in the schema. The tool description adds no additional meaning beyond what the schema provides; it merely references the parameters indirectly. Thus, baseline of 3 is appropriate.

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 (submit OTP), the resource (email addition), and the outcome (completes add-email flow). It distinguishes itself from siblings like verify_2fa and confirm_domain_email_code by specifying the email context.

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?

Explicitly states the prerequisite of having a Proof account and provides two authentication paths (client authenticate or start_login). It implies the add-email flow context and instructs to call again after starting a session, which gives clear when-to-use guidance. It doesn't explicitly mention alternatives like submit_verification_code, but the flow is sufficiently specific.

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