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

Annotations already declare readOnly, idempotent, non-destructive, openWorld, so safety is covered. The description adds genuinely useful behavioral context beyond that: the asset is free with a daily per-caller quota, and payment/auth material travels in MCP request headers (X-Payment / X-Payment-Tx / Authorization: Bearer fg_…) rather than in arguments. It also quantifies the return shape as 'top 3 official records'. It stops short of describing what happens when the daily quota is exhausted.

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 English hook is front-loaded and effective, but the body is heavily redundant: the Chinese block repeats the same offer plus '免费' and '入参：无' that the English block already states. The marketing framing ('Ask ...', '不用自己算') and the duplicated vendor-asset sentence inflate length without adding decision-relevant information. Bilingual support is defensible, but the content should not be restated twice.

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?

There is no output schema, so the description carries the return-value burden, and it does so reasonably: it enumerates the metrics returned (totals, approval rate, best/worst scheme, year-over-year change) and states the preview is capped at 3 records. Quota model and auth placement are also covered. The one gap is behavior on quota exhaustion or error, which an agent planning retries would want.

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 tool takes zero parameters, so the baseline is 4. The description reinforces this explicitly with '入参：无' / 'Args: none' and clarifies that credentials must go in HTTP headers instead of parameters, which prevents a plausible misuse. No further parameter meaning is needed.

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 concrete resource and payload: 2025 applications, approvals, approval rate, highest/lowest-approval scheme, and the top 3 official records for Hong Kong talent entry schemes. That is a specific verb+resource statement an agent can match to a user question. It does not name its siblings (scheme_list, approval_analysis), but the phrase '先看结论再决定要不要全量' signals this is the lightweight preview step, which partially differentiates it.

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?

Usage is implied rather than stated: the opening 'Ask "how hard is it to get a Hong Kong talent visa"' frames the entry question, and '不用自己算，先看结论再决定要不要全量' hints that a fuller data pull exists afterward. However, no alternative tool is named and no explicit when-not condition is given. An agent gets a rough sense of fit but must infer the boundary with scheme_list and approval_analysis itself.

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