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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-annotation context — it is free, requires no key, and carries limits/caveats plus membership information. Those additions are real but vague: the limits and caveats are never specified, and no rate or quota behavior is disclosed.

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?

Two short sentences with no filler, and the most decision-relevant facts (free, no key needed) are stated up front. The only soft spot is the trailing 'limits and caveats' clause, which spends words without conveying specifics.

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 simple, zero-required-param, read-only tool with no output schema, the description covers identity, cost and authentication adequately. It still leaves two gaps an agent would want: what the preview actually returns (data vs. explanatory content) and what the language parameter does.

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?

There is one optional parameter (language, enum zh/en) with 0% schema description coverage, so the schema does not compensate. The description never mentions the language parameter or what effect it has on output, leaving the agent to infer that it controls response language. With low coverage and a non-empty parameter list, the description should have carried this burden and does not.

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 names the resource it exposes (dated business evidence and launch signals) and frames it as a free preview, so an agent can broadly tell what it returns. However, the verb is fuzzy — it is unclear whether the tool returns sample data, documentation about the product, or both, since 'explains membership access, limits and caveats' reads like meta-content rather than a data operation. It also does not distinguish itself from siblings such as search_startup_cases or get_startup_radar.

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?

'Free preview' and 'no key needed' imply the usage context: an unauthenticated or pre-membership agent exploring the service before committing to a keyed tool. That is meaningful implicit guidance, but there is no explicit when-to-use/when-not-to-use statement and no routing to alternatives like build_startup_plan or search_startup_cases.

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