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

Beyond the annotations (readOnly, openWorld, idempotent, non-destructive), the description discloses that the tool uses a full browser, returns an inline image plus a link and markdown text, consumes significant context, and costs 3 credits. This adds valuable behavioral 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 well-structured with clear sections (when to use, when not, returns, cost) and front-loaded with the core purpose. The bilingual format doubles the length but does not add fluff; it remains efficient and scannable.

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?

Since there is no output schema, the description fully explains the return values (inline image, file link, markdown text) and also covers cost and context implications. For a simple two-parameter tool with solid annotations, this is complete and sufficient.

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 input schema already covers 100% of parameters with detailed descriptions (url format, maxChars range and default). The description does not add extra parameter-level semantics, so the baseline score of 3 is appropriate.

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 a specific action: opens a page in a full browser and returns a screenshot, a link to the full-size file, and page text in markdown. It distinguishes itself from siblings by explicitly contrasting with read_url and extract, and by emphasizing the visual need case.

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 explicit when-to-use and when-not-to-use conditions, naming alternatives (read_url for text-only, extract for specific values) and even comparing costs (1 credit vs 3). This is exemplary guidance for an agent.

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