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

Annotations already provide readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds valuable non-obvious context by disclosing the $0.02 per-call billing and that 4xx/5xx responses are not charged.

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?

Two tight sentences deliver the core behavior and the billing caveat with no filler. The main purpose is front-loaded and every clause adds information.

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 simple read-only tool with only two required parameters, an output schema, and rich annotations, the description is complete: it states the returned metrics, target/date scope, and cost behavior. Nothing essential is missing for an agent to invoke 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?

Schema description coverage is 100%, so both 'target' and 'date' are already fully documented in the schema. The description restates these concepts without adding new format, default, or edge-case details, so the baseline of 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?

The description names a specific verb ('Return'), a specific resource (Ahrefs Domain Rating and Ahrefs Rank), and the exact scope (target domain, given date). It clearly differentiates from siblings like get_semrush_domain_overview and get_similarweb_ranking by calling out the Ahrefs-specific metric.

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?

The description gives no guidance on when to choose this tool over the many sibling SEO/metric tools, nor does it mention exclusions or alternatives. The use case is only implied by the Ahrefs-specific naming.

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