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

Annotations already cover read-only and open-world, so the bar is lower, and the description still adds genuinely non-obvious behavior: sorted ordering by link strength and a concrete cost model ($0.02 per call plus per-row fee). It omits anything about rate limits or truncation at the 200-row limit, but the pricing disclosure is the high-value addition here.

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 short sentences, zero filler: the resource and return fields come first, then the cost note. Every clause carries information an agent would otherwise have to guess.

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 usefully enumerates the returned columns (rank, backlink count, spam score, first-seen date) and discloses cost, which is enough to call the tool confidently. The only gap is behavior at the row limit and whether the result set can be paged beyond 200.

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 both parameters (target domain, limit 1–200 default 50) are documented in the schema. The description adds no syntax, format, or validation meaning beyond what the schema already states, so baseline 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?

States a specific resource ('Domains linking to the target') plus the returned fields and ordering ('strongest first'), so the agent knows exactly what it gets. It does not name or differentiate itself from the sibling backlinks_summary, which is the main thing keeping it from a 5.

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?

No explicit when-to-use guidance and no mention of alternatives such as backlinks_summary or domain_overview. Usage is only implied by the resource itself; an agent must infer that this is the per-domain listing versus a summary.

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