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

Annotations already provide readOnlyHint=true and openWorldHint=true, covering the safety profile. The description adds behavioral details beyond annotations: it returns *rendered* HTML (implying JS execution) and explicitly notes JavaScript rendering support, plus a cost per call. This provides useful context without contradicting annotations.

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 description is extremely concise: two short sentences (one in English, one in Korean) plus a cost note. The main action is front-loaded, the JavaScript capability is a key differentiator, and the cost is practical information. No wasted words.

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 one-parameter tool with full schema coverage, good annotations, and no output schema, the description is largely complete. It explains the return value (HTML source), a key capability (JS rendering), and cost. It does not cover error handling or redirects, but these are not essential given the tool's simplicity.

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?

The schema has 100% coverage for the single 'url' parameter with an example, so the baseline is 3. The description does not add extra parameter-specific semantics beyond restating that a URL is entered. It does imply the URL can point to any web page (including dynamic ones), but that is not a significant extension of the schema's meaning.

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 clearly states the tool fetches a web page and returns its rendered HTML source. The specific verb-resource pairing (fetch + web page HTML) distinguishes it from siblings like url_screenshot (image) and url_similarity (similarity). Mentioning JavaScript rendering further differentiates it from a simple HTML fetcher.

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 description provides clear context for when to use this tool, particularly for pages that require JavaScript rendering ('자바스크립트 렌더링이 필요한 페이지도 처리됩니다'). It does not explicitly name alternatives or exclusions, but the context of extracting HTML is well established, and the cost note adds practical guidance.

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