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

With no annotations, the description carries the full burden and does so richly: it discloses the cache-only nature, the crucial semantic that status=missing means 'not cached' rather than zero traffic, the Pro-only gating of include=search, and precise credit costs (1, 10, or 0) tied to saved-ranking status. These are exactly the behavioral traits an agent needs and none are recoverable from structured fields.

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 the core purpose, then options, cache semantics, triggers, and cost in a logical order. It is dense and the final credit sentence is somewhat convoluted, but nearly every clause carries information an agent needs.

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 no output schema and no annotations, the description must compensate, and it largely does: it enumerates the returned data families, explains cache/status semantics, and covers cost and access tier. Only the exact per-status response shape is left implicit, a minor gap for a cached-lookup tool.

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 already 100%, so the baseline is 3. The description still adds value by expanding what include=baidu and include=search actually return (ranked keywords, landing pages, competitors) and by tying include=search to credit spend, going beyond the schema's terse 'Pro-only' note.

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?

Opens with a specific verb and resource ('Read a cached Vaneform domain snapshot') and enumerates exactly what comes back (scale visits, registry, site profile, link-rank popularity). The 'cached' qualifier implicitly separates it from live-research siblings like research_site, so an agent can place it without opening a schema.

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 a concrete trigger list ('Use for 查网站, 访问量, how big a site is, domain visits, registry age, backlink rank, 百度权重, 关键词排名'), which maps task intent to this tool well. It does not, however, name an alternative or state when NOT to use it (e.g., versus research_site or compare_bulk), leaving the routing decision partly to inference.

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