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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the description wisely spends its words elsewhere: it discloses the pricing model (¥0.3/次) and, importantly, that only successful calls are billed with automatic refund on failure or empty results. That billing/refund behavior is not derivable from any structured field and affects how an agent should batch or retry calls. Return-field surface is also disclosed in the absence of an output schema.

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?

Three short sentences: purpose, return fields, use cases, cost. Front-loaded with the verb and resource, with no redundant restatement of the title or annotations.

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?

For a simple two-parameter read with no output schema, the description covers purpose, return surface, use cases, and cost/refund behavior — enough to call correctly. It does not say what happens on unknown/invalid usernames versus empty profiles, a minor gap for a lookup tool.

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% and both parameters (username, _token) are documented in-schema, including the recommendation to use the X-FW-Token header instead. The description adds no syntax, format, or resolution guidance for the username 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 (获取视频号账号资料) and enumerates what comes back (昵称、粉丝数、获赞数、简介、认证状态), which distinguishes it from the channels_post_* and channels_search_* siblings. It does not explicitly name a sibling it overlaps with (e.g. channels_user_posts), so it stops short of a 5.

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 when-to-use scenarios: 达人筛选、账号画像、粉丝量级分组. These clearly frame the tool as a one-shot profile lookup rather than a post enumerator. No explicit exclusions or 'use X instead' routing, which keeps it from a 5.

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