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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds real behavioral value beyond that: it says known terms (首充、优惠、合约), unknown fields, and channel data dates are preserved as-is, which tells the agent the payload is a faithful, unnormalized read, and it explicitly states no application is submitted.

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 tight sentences with the primary action and input source front-loaded, followed by the data-fidelity caveat. No filler, though the second sentence is a dense list that could be slightly leaner.

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?

With no output schema, the description carries the burden of hinting at return content, and it does so by naming the clause categories and noting unknown items and channel data dates are kept. Combined with annotations covering safety, an agent has enough to call it correctly; only the response shape and error behavior for an unknown slug are unaddressed.

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 a single parameter and schema description coverage is 100%, with the schema itself documenting the slug, its origin in search_plans, and its pattern. The description restates the same slug provenance without adding format or edge-case detail, so the schema is doing the work — baseline 3.

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 (读取) and resource (在售套餐) and pins the input to a slug produced by search_plans, so the agent can tell it apart from the search tool. It does not, however, say anything about how it differs from compare_plans, leaving one sibling undifferentiated.

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 a clear precondition for use — call it with the slug returned by search_plans — which implicitly routes the agent to search first, then fetch details. It also marks a boundary ('不提交申请'), but never mentions compare_plans as an alternative for multi-plan comparison, so the when-not guidance is partial.

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