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

Annotations already cover readOnly, idempotent, openWorld and non-destructive, so the safety profile is established. The description adds genuinely new behavioral facts beyond those annotations: pricing at ¥0.2 per call billed only on success, with automatic refund on failure or empty results. It does not discuss rate limits or response envelope details, which keeps it from 5.

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 first clause front-loads what the tool is and what makes it distinct, followed by return fields, capabilities, use cases, and billing. Every sentence carries information, though the single dense paragraph would scan better split into capability and billing lines.

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 8 parameters and no output schema, the description compensates by listing the returned fields (title, cover, duration, publish time, export ID, source account), which is exactly what's needed. Pagination behavior via cursor/offset is left to the schema, a minor remaining gap.

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 coverage is 100%, so the schema already documents all 8 parameters, and the baseline is 3. The description adds a Chinese semantic mapping for sort (相关性/最新/最热) and confirms time and duration filtering, but it does not explain cursor vs. offset interplay or the raw flag, so it only marginally exceeds the schema.

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 (search 视频号 videos) and explicitly scopes it as the WeChat 搜一搜 video vertical, '不是号内搜索', which distinguishes it from channels_search_in_channel. It also enumerates the returned fields, so the agent knows exactly what it gets.

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 usage scenarios (视频号选题、达人挖掘、品牌舆情巡检) and an explicit exclusion (not in-channel search). It does not name the alternative sibling tool by name, so the agent must infer that channels_search_in_channel is the counterpart, which keeps it just short of a 5.

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