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

Discloses a lot beyond the annotations: the result is a top-N sample, not the complete profile; default 10 rows and a 1–50 limit; no cursor; provider stores up to 100 ranked rows, one per referring domain; shared 14-day cache with fresh:true triggering external endpoints; provider work is billed and retries can repeat work; no Scan allowance consumed. This explains the non-readOnly/non-idempotent annotation posture rather than contradicting it.

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-loaded with the payload contents and primary use, then layered with the important caveats. Dense but nearly every sentence carries operational value; the billing/cache sentences are a touch heavy but earn their place.

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 a full output schema present, the description need not explain return shapes, and it still covers scope, sampling limits, caching, billing, and idempotency risk. Nothing an agent needs to call it correctly is missing.

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: 'fresh:false is not cache-only' reframes the fresh flag materially, and it clarifies the sample-vs-complete distinction governing the limit parameter.

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 verb+resource ('A domain's backlink profile') and enumerates exactly what it returns: referring domains, total backlinks, domain rank, spam score, dofollow ratio, plus top individual backlinks. It is clearly distinguishable from sibling SEO tools like get_seo_page_audit, get_seo_keyword_metrics, and get_seo_search_results.

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?

Explicitly tells the agent when to use it ('gauge a domain's link authority and compare it against competitors') and names a companion tool (list_competitors). It stops short of stating when NOT to use it or naming a direct alternative that does the same job, so it falls just short of a 5.

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