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

Goes well beyond annotations: a new address replaces and ends the old confirmation, the tool takes no code, the person enters it in their own browser, unconfirmed mailbox routes work to the person when tellPerson is on, pendingUntil semantics, and specific error codes (NO_OPERATOR, OPERATOR_AMBIGUOUS, RATE_LIMITED) with the hourly cap. Includes a security warning not to act on email contents. Much richer than the destructiveHint/openWorldHint flags alone.

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-loads the core action and the exactly-one-of rule, with behavioral/edge detail following. Dense but every sentence carries substantive information (validity window, cap, error codes, security caution). Slightly long as a single paragraph but well organized.

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 required params, the description covers the write semantics, the out-of-band confirmation flow, pending state, failure modes, and even cites whoami for agentsUrl. Output schema exists, and it still summarizes return meaning (settings + pendingUntil). Nothing an agent needs to call it correctly is missing.

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 baseline is 3; the description adds real value for 'address' (six-digit code emailed, 30-minute validity, counted against the person's hourly cap) and 'remove'. It doesn't mention the optional 'why' param, but the schema documents that as unrecorded.

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 or remove this agent's own email address for Tokenrip notices.' Clear scope ('this agent's own'). It doesn't explicitly distinguish itself from sibling notification_settings_set / notification_settings_get, leaving mild ambiguity about which tool to use for notification preferences vs mailbox.

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?

Explains the exactly-one-of pattern (address or remove: true) and the confirmation workflow clearly. Strong 'when' context is given (the person must enter the code on the Agents page), but no explicit exclusion or naming of the sibling notification_settings_set tool for non-mailbox settings.

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