count_bill

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

无注解，因此描述承担了行为披露责任。说明了返回 JSON 格式、is_exact 字段含义、以及估算与实际行数的关系，还提示了分片查询建议，行为透明性较好。

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?

描述结构清晰，包含用途、返回格式、参数说明，每部分都有实质信息，没有冗余。长度适中，关键信息前置。

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?

在输出 schema 之外补充了返回字段语义（is_exact 含义、estimated_rows 下限），并给出了使用场景和参数示例，对于仅2个参数的轻量计数工具已足够完整。

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 本身无属性描述（0% 覆盖），但 Args 部分对 form_id 和 filter_string 都给出了格式说明和具体示例（如表单ID和日期过滤条件），充分补偿了 schema 的不足。

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?

描述以'估算'这一具体动词开头，明确资源是'某查询条件下的数据行数'，并强调'不返回数据内容'，与 query_bill 等返回数据的兄弟工具形成清晰区分。

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?

说明'用于大数据量查询前的探测'，给出了明确的使用场景；当 is_exact=false 时建议按月/周分片查询，提供了后续操作指导。虽然没有显式点名替代工具，但已隐含与查询类工具的分工。

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