start_add_email

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

Annotations only cover the read/destructive profile; the description goes well beyond by disclosing the external side effect (an OTP email is sent), the return artifact (a session ID), and the precise authentication prerequisite (PROOF_API_KEY or start_login). This is exactly the behavioral context an agent needs before invoking.

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?

Purpose and mechanics are front-loaded in the first two sentences, with the ACCESS provisioning note clearly separated below. Efficient overall, though the ACCESS paragraph is slightly long relative to the one-parameter scope.

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 single-parameter initiation tool, the description covers purpose, side effects, the returned session ID, and the auth prerequisite. Nothing an agent needs to call it correctly is missing, and there is no output schema that would need explaining.

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% with a single well-described 'email' field, so the schema carries the param burden. The description only confirms the destination of the OTP, adding no format or constraint detail beyond the schema; baseline 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?

States a specific verb+resource ('Start adding a new email address') and immediately clarifies the mechanism ('Sends an OTP code', 'Returns a session ID'). This clearly separates it from siblings like start_add_phone, verify_email_otp, and list_emails.

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 establishes the multi-step workflow (start → OTP → verify with session ID), so an agent understands where this tool fits and what follows it. It lacks an explicit 'use this instead of X' comparison, but context for selection is clear.

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