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

With no annotations, the description carries the full burden of behavioral disclosure. It states the core action and an access requirement but does not reveal potential side effects like invalidating a previous OTP, rate limits, or error behavior for invalid sessions.

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 compact and front-loaded. The first sentence states the purpose, and the second block clearly labels access requirements. No filler or redundancy; every sentence contributes necessary context.

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 one-parameter tool with full schema coverage, the description is mostly adequate but omits how the add-email session is created (presumably via start_add_email). It also provides no guidance on expected output or failure modes, which is notable since there is no output schema.

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 already defines session_id as 'Add-email session ID' with 100% coverage, so the baseline is 3. The description references 'in-progress email addition' and mentions session creation via start_login, but it does not add substantive detail about how to obtain or format the session_id 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 states a specific verb and object: 'Resend the OTP code for an in-progress email addition.' This precisely identifies the action and resource, and the 'email addition' context distinguishes it from siblings like verify_email_otp or resend_verification.

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 gives clear access prerequisites (needs a Proof account, authenticate or sign in with start_login) but does not provide explicit when-to-use versus alternative tools. It implies usage for an in-progress email addition but never names siblings or exclusion conditions.

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