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

Goes well beyond the annotations (readOnlyHint=false, openWorldHint=false, destructiveHint=false) by disclosing the rate limit (at most one email an hour), the content (names only, never message text), the two-step confirmation flow (link + 6-digit code), that nothing is sent until confirmation, and the privacy guarantee (address never shown). Rich behavioral context an agent cannot infer elsewhere.

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?

Front-loaded with the core purpose, then the event list, rate limit, prerequisite, and confirmation flow. Dense but every clause carries real information; slightly long as a single run-on paragraph, keeping it from a 5.

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 mutation tool with no output schema, the description fully explains the observable outcome (a confirmation email with link and code, nothing else sent until confirmed), the follow-up step, and the rate/privacy behavior. An agent has everything needed to call it and expected next action.

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 description coverage is 100% with only two params, so the schema already documents both email and api_token, including the 'ask them first' caveat. The description adds no email-format or token-transport detail beyond the schema, so the baseline 3 applies.

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 (set notification email) and the exact scope: emails the human on new hashn events (knock, message, payment request/payment, delivered file). It also routes to the sibling confirm_notification_email, so an agent can distinguish this from confirm/remove/notification_status without opening a schema.

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?

Gives clear context ('let your human get an email when something new happens') and a prerequisite ('Ask them first'), plus the follow-up path via confirm_notification_email. It does not explicitly frame when-not to use it or name remove_notification_email/notification_status as alternatives, so it falls short of full routing guidance.

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