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

Annotations already cover readOnly/idempotent/openWorld, and the description adds information annotations cannot express: per-call pricing (¥0.1), billing only on success with automatic refund on failure or empty results, page-based return, and a hard pagination ceiling beyond which upstream returns nothing. Those are exactly the cost and completeness signals an agent needs before spending calls.

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?

Purpose comes first, followed by returned fields, use cases, pricing, and the pagination limitation — a sensible front-loaded order with no filler. It is a dense run of clauses, but every sentence carries information the agent would otherwise have to guess.

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 compensates by listing the returned fields and pagination behavior, and it adds billing and depth limits. The one real gap is that it never states whether replies are included or require ig_sub_comments as a follow-up, which matters for an agent planning a full comment crawl.

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 code, _token, and min_id are already fully documented with formats and inheritance of next_min_id. The description reinforces the shortcode-based call model and page-wise pagination but adds no syntax or constraints beyond the schema, so the baseline of 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?

The description states a specific verb and resource ("获取Instagram帖子评论") plus the invocation key ("按帖子短码调用") and enumerates the returned fields. It implicitly distinguishes itself from ig_sub_comments by returning only a reply count rather than expanding replies, but that boundary is never stated explicitly.

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?

It gives concrete use contexts ("评论情感分析、竞品口碑对比或舆情监测") and a scope limit ("翻页深度受平台可见范围限制"), which tells the agent when to reach for it. It stops short of naming alternatives such as ig_sub_comments for replies or ig_post_detail for the post itself, so the routing decision is left partly to inference.

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