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

Annotations already declare read-only, idempotent, non-destructive behaviour, so the description's job is to add operational context — and it does: 'strongest first' ordering, a 100-row ceiling, inclusion of target totals, and per-call billing with data. What's missing is whether results can be paged beyond the cap, which matters for a capped read.

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?

Three compact sentences with zero filler: what it returns, how much, and what it costs. The resource definition and ordering are front-loaded before the limit and billing details.

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, the description carries the burden of describing returns, and it does so by listing the row fields plus target totals. The billing disclosure fills a gap annotations can't cover; only the absence of any pagination/cap-escape note keeps it from full marks.

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 parameters are documented in structured form; the description nonetheless adds semantics the schema lacks, namely that results are ordered by link strength and that totals accompany each page of rows. The dofollow field is echoed from the schema but the ordering/ranking semantics are genuinely additive.

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 concrete resource (backlinks or referring domains for a domain/page URL) and enumerates the returned fields, so an agent knows exactly what data comes back. It does not explicitly contrast with adjacent siblings like domain_overview or ranked_keywords, but the resource is specific enough that confusion is unlikely.

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 'backlinks or referring domains' phrasing implies mode selection but never states when to choose one mode over the other, nor when to use this tool instead of domain_overview or ranked_keywords. Usage is implied rather than directed.

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