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

Annotations already establish readOnly and non-destructive behavior, and the description adds substantial behavioral context: pricing per size, free repeated empty lookups, the quote-id confirmation requirement for size 1000, and the return of top `limit` domains plus total_count. This lets the agent predict side effects and cost before calling.

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?

The description is compact and front-loaded: the core purpose appears in the first sentence, followed by cost behavior and return summary. Every sentence adds distinct information; there is no filler or redundant restatement of the tool name.

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?

Despite having no output schema, the description discloses the output fields, the default and maximum return count, the total_count field, pricing, and the confirmation edge case for size 1000. An agent has enough information to invoke the tool correctly and interpret its result.

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 the baseline is 3, but the description adds meaning beyond the schema: it clarifies that `limit` applies to the strongest-first ordering and explains the quote/confirm workflow around `confirm_quote_id`. The cost-to-size mapping is also reinforced in prose rather than left to the schema alone.

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 clearly identifies the resource: 'Domains linking to a target' and enumerates the returned metrics, so an agent can infer what the tool does. However, it never contrasts itself with sibling tools like backlinks_pages or backlinks_list, so it misses the opportunity to differentiate at a glance.

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 operational guidance for cost tiers, free empty lookups, and the size-1000 quote confirmation flow, which is useful when invoking the tool. It does not explicitly state when to prefer this tool over sibling backlinks_* tools or what conditions would make an alternative more appropriate.

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