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

With no annotations, the description carries the burden and does disclose that lower-tier plans return 403, which is a meaningful failure mode. It also lists the return fields, giving the agent expectations about the output. It doesn't mention rate limits or pagination, but the plan requirement is substantial context.

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 compact and well-structured: a one-line purpose, plan constraint, Args list, and Returns list. It front-loads the purpose and every section serves a distinct function.

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 moderate query tool with 5 optional parameters, the description covers the plan requirement, parameter formats, and return schema. It lacks explicit defaults for omitted parameters, but the overall information is sufficient for an agent to invoke the tool correctly.

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 input schema already describes all 5 parameters with 100% coverage, so the description's parameter section adds little beyond repeating the schema. It does provide an example symbol format and enumerates the allowed values for trade_type and holder_type, which matches the schema's descriptions.

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 clearly identifies the tool as querying "重要股东增减持（行情数据）" (major shareholder increase/decrease holdings market data), which is a specific resource and distinguishes it from siblings like shareholders or block_trade. The verb is implied (query/list), but the resource is unmistakable.

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?

The description notes the PRO+ plan requirement and 403 error for lower tiers, giving a concrete precondition. However, it doesn't explicitly state when to choose this over sibling tools like shareholders or top_list, nor does it provide exclusion criteria.

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