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

Annotations indicate readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description expands on this by noting real browser rendering, output as base64 JSON or raw bytes, ad blocking, and pricing ($0.04 per call via x402). It does not contradict annotations and adds behavioral traits beyond what annotations provide.

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 a single paragraph of 4 sentences, front-loaded with the key purpose. It is clear and without waste. However, it could be slightly more structured (e.g., bullet points for options) to improve scanability.

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?

Given the tool's complexity (6 parameters, output schema exists, 1 required parameter), the description covers all essential aspects: purpose, output format, options, pricing, and ad blocking. With an output schema, return values are covered; the description is complete for agent decision-making.

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% (all 6 parameters have descriptions). The description restates key options ('width 320-1920 (default 1280), height, full_page=1, format=png|jpeg') but adds no new meaning beyond the schema. The baseline is 3, and the description provides marginal value by summarizing defaults.

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 starts with 'WEBSITE SCREENSHOT' and states 'render any public URL in a real browser and get the pixels.' The verb 'render' and resource 'URL' are specific, and the tool is clearly about capturing a screenshot. It distinguishes from sibling tools like get_scrape (text extraction) by focusing on visual capture.

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 lists explicit use cases: 'visual QA, previews, archiving, design reference.' It also mentions automatic ad/cookie banner blocking. However, it does not provide when-not-to-use or suggest alternatives, though the use cases provide clear context for selection.

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