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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open-world), so the bar is lower, and the description adds real value beyond them: a $1 USDC x402 charge and the fact that errored calls are not billed. It also discloses the shape of the plan (ordered records, click-path steps, staged DMARC rollout).

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 packed with concrete deliverable detail; every clause (record actions, ordering, click-paths, rollout, lock-down set, pricing) carries information. Slightly dense, but nothing is wasted or repeated.

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?

With no output schema and no annotations explaining returns, the description carries that burden well, spelling out exactly what comes back (records with name/value/why and action, in order, plus host-specific steps and a staged rollout). Cost and error-billing behavior are also covered, leaving no material gap for invoking it correctly.

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?

There is a single parameter and schema description coverage is 100%, so the schema already documents the domain format (including that an email or URL works). The description's 'for one domain' adds scope framing but no syntax or format detail beyond the schema, matching the baseline 3 for a fully documented single parameter.

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 names a specific verb+resource ('Email security fix plan for one domain') and enumerates the deliverable: SPF, DKIM and DMARC records with create/replace/keep actions, ordered, plus DNS-host click-paths and a staged rollout. This is clearly distinguishable in substance from the check/score siblings, though it never names an alternative to sharpen the contrast.

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 implied rather than stated: an agent can infer this is the remediation step after check_domain_email_security or email_security_score, but the description never says when to reach for it versus those siblings. The only conditional guidance is the behavioral note that non-sending domains get a lock-down set, which is about output, not tool selection.

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