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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is fully covered elsewhere. The description adds only a list of returned metrics, which is largely redundant with the existing output schema, and says nothing about rate limits, caching, or failure modes.

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 action and payload in a single efficient sentence, followed by a short pointer. No filler or repetition of the title. The 'Related: whois' fragment is minimal but doesn't clutter.

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 rich output schema and full annotation coverage on a read-only, idempotent single-parameter tool, the description is close to sufficient. Its only real gap is the absence of guidance about when this analysis is the right one to call relative to the many sibling SEO tools.

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?

The single 'domain' parameter has 100% schema description coverage, including format constraints (bare domain, no protocol/path/port, punycode for IDN), so the schema carries the full burden. The description adds no additional parameter meaning, which matches the baseline 3 for high coverage with a non-zero parameter count.

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 (Return) and resource (a domain's backlink profile) and enumerates the profile components (domain rank, total backlinks, referring domains, spam score, link distribution). It does not differentiate itself meaningfully from the many sibling analysis tools beyond a bare 'Related: whois' pointer, which is about a different tool rather than a contrast.

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?

There is no explicit when-to-use guidance, no prerequisites, and no statement of when another sibling (e.g. keyword_data, tld_rank, whois) would be the better choice. The trailing 'Related: whois' hints at adjacency but offers no selection criteria.

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