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

Goes well beyond the annotations: it names what gets overwritten ('replace its saved verification proof'), discloses hidden side effects ('may finish provider inbound routing, inbox and webhook setup'), clarifies a negative side effect ('Sends no email'), and states the permission model ('Any member of the business may check'). This is exactly the mutation/permission context the destructiveHint and non-idempotent hints cannot convey.

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?

Four dense sentences, front-loaded with the action and its main effect; the 'empty list means the sender is ready' clause is slightly redundant given an output schema exists, but it is short and operationally useful. No filler or hedging.

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 destructive, open-world re-check call with a full output schema, the definition covers the mutation, downstream effects, and caller permissions. The only real gap is usage routing — it does not say how this differs operationally from simply fetching sender state or how often to re-check.

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% and the schema already documents both parameters, including where sender_id comes from. The description adds no syntax, format, or constraint detail beyond that, so the baseline 3 applies even though nothing is misleading.

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 and resource — 'Re-check a sending domain's DNS records with the email delivery provider' — plus the concrete effect of 'replace its saved verification proof'. The 're-' prefix implicitly separates it from the initial request_email_sender step, so an agent can tell which phase of the flow this belongs to.

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?

Usage is only implied: 'Re-check ... now' and the sender_id provenance ('from request_email_sender or get_email_campaign') suggest it is the follow-up step after requesting a sender. There is no explicit when-not guidance, no mention of polling cadence, and no named alternative to use instead if the agent just wants status without re-verification.

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