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

With no annotations, the description carries the behavioral burden and does well: it discloses cache-only behavior, Pro-only access for include=search, credit costs (1 credit normally, 200 credits when search returns saved ready/partial rankings, 0 credits when missing/error), and the meaning of status=missing. It does not cover rate limits or invalid-domain handling, but the main behavioral traits are surfaced.

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 dense but front-loads the core resource and then layers optional includes, cache caveats, usage triggers, and credit costs. Every sentence adds operational value, though the credit-cost sentence is somewhat convoluted and the use-case list could be trimmed slightly.

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 two-parameter, no-output-schema, no-annotation read tool, the description is strong: it explains cache-only semantics, include families, Pro-only search behavior, status meaning, and credit costs. It does not describe return value structure or error handling beyond status=missing, but it is otherwise complete enough for correct invocation.

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. The description adds meaning beyond the schema by explaining that include=baidu is cached Baidu rank, include=search returns Pro-only keyword rankings (ranked keywords, landing pages, search competitors) from this month's cache, and by spelling out credit implications tied to those include values.

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 uses a specific verb ('Read') and resource ('cached Vaneform domain snapshot') and enumerates the returned families (scale, registry, profile, popularity, baidu, search). It is very clear what the tool does, but it does not explicitly distinguish itself from siblings such as lookup_keyword or compare_tld, so it falls short of 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?

It gives concrete usage triggers ('Use for 查网站, 访问量, how big a site is...') and important exclusions such as 'Cache-only: status=missing means not cached, not zero traffic.' It does not name sibling alternatives or say when to prefer compare_bulk or lookup_keyword, so it is clear but lacks explicit routing.

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