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

Annotations already declare read-only, idempotent, open-world, and non-destructive behavior. The description adds the sourcing mechanism (HKEX disclosure filings), the exact returned fields, and the HKEX-only coverage caveat, which is meaningful behavioral context the annotations do not provide.

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 purposeful: definition, contrast, search keywords, example queries, data source, return fields, and limitation. It is longer than a one-liner, but each component adds navigational value for agents dealing with a multi-language, mixed-purpose tool.

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?

Without an output schema, the description still clearly lists the return contents and the coverage_note, while also explaining data provenance and limitations. An agent has enough context to invoke the tool correctly and interpret its response.

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 description coverage is 100% with clear parameter descriptions, so the baseline is 3. The tool description reinforces the month/date and query use cases through examples, but it does not add substantial parameter semantics beyond the schema.

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 a specific verb and resource: NMPA drug-APPROVAL events, including marketing clearance, conditional approval, and expanded indications. It explicitly contrasts itself with nmpa_updates, which covers regulatory policy news, so an agent can tell them apart.

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 provides concrete example queries, states the alternative tool nmpa_updates, and clarifies when its coverage is incomplete because it only covers HKEX-listed companies. This gives the agent both when-to-use and when-to-expect-limitations guidance.

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