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

With no annotations, the description carries the burden and does well: it declares the tool read-only, discloses that the return structure differs by market (A-share event summary vs HK daily detail) with the exact column sets, and states the subscription tier required (Standard ¥29.9+). It omits behavior for empty ranges and any pagination or result-size limits.

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-loaded with the purpose and trigger questions before the structural warnings; every sentence carries content. Heavy use of emoji/warning markers adds visual noise without adding information, keeping it from a 5.

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?

Even though an output schema exists, the description proactively explains the market-dependent return shape that an agent would otherwise mis-parse, plus the access tier and sibling distinction. Nothing needed to call or interpret it correctly is missing.

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% (code, start, end all documented), so the schema already does the parameter work. The description adds no syntax or format guidance for the date range or the sh/hk code prefix convention beyond what the schema states, so baseline 3 applies.

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?

States a specific verb and resource (company share buyback records) and explicitly distinguishes itself from the closest sibling, ashare_shareholder, as 'the company buying itself' vs 'who holds shares'. An agent can route correctly without opening either 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?

Gives concrete user-question triggers ('is this company buying back / how much / at what price') and names the alternative tool with the distinction that separates them. Both when-to-use and when-not-to-use are present.

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