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

Beyond the readOnlyHint/openWorldHint annotations, it discloses cost behavior (成功扣减 20 积分，失败不扣费), data semantics (median values, cooperation scope includes 进店 fields while daily returns null, no cross-date summation, missing dates are not zero-filled), and response shape (business fields plus points). These are material operational facts an agent cannot infer from annotations.

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?

Dense but front-loaded: purpose, then usage, then behavioral caveats. Every clause carries information, though a few points (口径不可混用, 成本口径见字段说明) are repeated across description and schema, adding mild redundancy.

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 an output schema present, return values need not be enumerated, and the description still confirms what success returns. Combined with cost semantics, scope caveats, and explicit sibling routing, an agent has everything required to call this 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?

Schema description coverage is 100%, so the baseline is 3; the description adds meaning by explaining what the cooperation vs daily scopes imply for 进店 fields and consumption rules. It reinforces the '不可混用' constraint but largely echoes the schema's own note_scope description, so it stops short of a 5.

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 precise verb and resource: fetching date trends and overviews of XHS Pgy creator exposure, reads, interaction medians and estimated cost. It scopes what is fixed (图文＋视频, 近30日, 全流量) and explicitly names the sibling tools that cover adjacent needs (商业概览 and 笔记表现), so an agent can distinguish it without opening schemas.

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?

Explicitly gives the trigger condition ('观察指标随时间变化时使用'), the selection rule for note_scope (daily vs cooperation), the hard exclusion ('不支持自选日期'), and routes split-by-format/commercial totals to 商业概览工具 and per-note performance to 笔记表现工具. When-to-use, when-not, and alternatives are all present.

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