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

Goes well beyond the annotations: discloses the Backlinks API dependency, the failure message when it is off, per-call billing against the agency's own DataForSEO account, cost and monthly-limit reporting in the response, and same-day caching behavior. These are exactly the side-effect and cost facts an agent needs before invoking.

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?

Front-loads what the tool returns in the first sentence, then layers prerequisite, cost, and caching facts. Four sentences with no filler, though the cost/caching detail is somewhat wordy and could be tighter.

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 read-only single-parameter tool with no output schema, the description covers the returned metrics, prerequisites, cost model, limit consumption, and caching – everything needed to call it correctly and interpret the response.

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?

Only one parameter and schema coverage is 100%, with the schema already specifying format ('example.com, without https:// or www.'). The description adds nothing about the domain argument, so the baseline 3 is appropriate.

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 (backlinks to a domain) and enumerates exactly what the summary returns: authority rank, backlink counts, referring domains, broken backlinks, spam score. It is clear what the tool does, though it never explicitly contrasts itself with related siblings like seo__domain_overview or seo__analytics, leaving the agent to infer the distinction.

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?

Provides useful operational context (Backlinks API must be enabled; calls cost the agency money; the same question within a day is served from cache at no cost), which implicitly guides when to reuse rather than re-call. However, it gives no explicit guidance on when to choose this tool over seo__domain_overview, seo__analytics, or seo__ranked_keywords.

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