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

Annotations only declare readOnly and openWorld; the description adds real behavioral context beyond them: results are Sogou redirect links rather than direct article URLs, heavy use may trigger a captcha returning 503, and billing is $0.002 USDC per successful call via x402 with failed calls uncharged. Pricing and failure semantics are exactly the kind of detail annotations cannot carry.

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 and source are front-loaded and every clause carries information: return fields, pagination, link behavior, failure mode, pricing. It is a single long run-on sentence, which hurts scanability slightly, but nothing is filler.

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 no elaboration, and annotations cover the safety profile. The description still rounds out the picture with result count, link semantics, the 503 captcha failure mode, and payment terms — everything an agent needs before calling a paid, open-world search.

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 both parameters are already documented in the schema, and the description largely restates them (10 per page, query scope). The only marginal addition is that queries may be Chinese or English, which the schema also implies. Baseline 3 applies when the schema does the heavy lifting.

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 (WeChat Official Account articles matching a query) plus the exact source (Sogou WeChat search, weixin.sogou.com). Against a sibling list crowded with news search tools, this makes the Chinese-language WeChat domain unambiguous.

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 clear operating context — query accepts Chinese or English, 10 results per page, pagination caps at 10 pages — and discloses the captcha/503 condition. It does not name an alternative sibling (e.g. search_google_search or search_news_across_the_web) or say when not to use it, so it falls 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.