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

Beyond the readOnly/openWorld annotations, the description discloses the transport ('public web API endpoint, not HTML scraping'), that no authentication is needed, and the credit cost model including repeat-charge behavior. However, the pricing statements conflict internally ('at least 10 Nexscope credits' vs '1 credit per request'), which undercuts the cost disclosure.

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 core two sentences are good, but the remainder is pasted pricing boilerplate with broken fragments ('Kwai Post API View Pricing Get public Kwai post details from a post URL. 1 credit per request Actual supplier units are reported per request.') that duplicates the purpose and contradicts the earlier credit figure.

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, listing the returned fields is necessary and done well, and the cost/auth context is covered. The only incompleteness is the unresolved cost ambiguity, which could mislead an agent budgeting a call.

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?

There is a single optional parameter with 100% schema description coverage ('Kwai post URL'), so the schema already carries the semantics. The description only repeats 'from a post URL' and adds no URL format, host, or validation guidance, 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?

The first sentence names a specific verb and resource ('Fetches public Kwai post details') and enumerates the returned data: caption, media URLs, cover images, counts, author info, music metadata. That clearly separates it from post-list/profile siblings, but the description never names the adjacent tools (social_kwai_profile, social_kwai_user_posts), so the agent must infer the post-vs-profile boundary.

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?

The phrase 'from a post URL' implies the precondition, but there is no explicit when-to-use, when-not-to-use, or named alternative. With sibling tools like social_kwai_user_posts and social_kwai_profile available, an explicit routing rule would have been valuable.

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