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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses the cost model ($1 USDC per call via x402), the conditional no-charge policy, and the async nuance that the core source is validated before the job is queued and charged. It also describes what the model produces (A-F grades across security, email, performance, SEO plus prioritised fixes and a PDF), which is exactly the behavioral detail an agent needs before spending money.

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?

It is one dense paragraph, but the audit scope is front-loaded and the pricing/refund/async caveats follow, so the agent reads the important information first. The enumeration of ten checks is long yet earns its place by defining the deliverable; no sentence is purely filler.

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?

There is no output schema, so the description carries the return-value burden and does so by naming the grades, the prioritised fixes and the PDF. For a paid, open-world, async-capable audit tool, the cost, refund condition and delivery modes are all covered.

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 75% and the schema already documents pdf, async and webhook_url, so the baseline is 3. The description adds marginal value by tying async to the 'job id now, report later' flow, but it says nothing about the required domain value's expected format or whether webhook_url requires async to be set.

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 states a specific verb and resource ('Full domain and website audit') and enumerates the ten passive checks it covers, so an agent knows exactly what comes back. What it does not do is differentiate itself from closely named siblings such as domain, domain_audit, report_seo or seo, which all sit in the same neighborhood.

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 context is implied rather than stated: the breadth of the audit makes it the heavy option, while the refund clause tells the agent when it will not be charged. There is no explicit steering such as 'use domain_audit for a quick single-factor check' or 'use dns when you only need records', so alternatives must be inferred.

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