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

readOnlyHint=true is consistent with a pure fetch, and the description adds real behavioral detail beyond annotations: scripts/styles/tags are stripped, output is auto-truncated to max_chars, and only publicly accessible http/https pages work. It stops short of describing failure modes (timeouts, redirects, empty-body pages).

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?

Four short sentences, front-loaded with purpose then trigger conditions then constraints. The inline example is the only slightly redundant element since the schema already shows the shape, but it is compact and harmless.

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 2-parameter read-only tool with full schema coverage and no output schema, the description covers what matters: what is returned (plain text body), how it is bounded (auto-truncation, max_chars), and the accessibility constraint. Missing only how failures surface to the caller.

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%, with both url and max_chars documented including the default 3000 and 10000 cap, so the baseline is 3. The description's concrete example input adds only marginal value and no format or edge-case guidance beyond 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?

The description names a specific verb and resource (抓取指定 URL 网页并提取正文纯文本) and gives the transformation details (去脚本/样式/标签，自动截断). None of the sibling tools (currency_convert, weather_query, ip_info…) overlap, so an agent can immediately place it as the web-reading tool.

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?

Explicitly states the triggering intents ('总结这个链接/读取网页内容/提取文章正文'), which is clear use-when guidance. It also excludes a class of targets ('仅支持公开可访问的 http/https 页面'), i.e. no login-gated or private pages, though it does not say what to do when a page is JS-rendered or blocked.

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