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

With annotations already covering readOnly, openWorld, idempotent, and non-destructive hints, the description adds valuable behavioral context: the per-call cost ($0.02), that the page is untrusted content to analyze not follow, the exact return fields (url, title, wordCount, markdown, rendered, untrustedContent), and payment/authentication requirements (MPP, npx agent402-mcp, AGENT_KEY, AGENT402_CREDITS_KEY). No contradictions with 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 relatively long but every sentence earns its place: the core functionality is front-loaded, followed by usage context, untrusted warning, return shape, and payment instructions. It is well-structured, scannable, and free of redundant 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?

Given the complexity (costs, authentication, untrusted content, payment methods) and existing output schema, the description covers all necessary operational details. An agent has everything needed to correctly invoke the tool and handle its result safely.

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 single parameter (url) is fully described in the schema (coverage 100%), and the description does not add additional semantic detail beyond what the schema already states. Per the rubric, baseline 3 applies when schema coverage is high and the description doesn't compensate further.

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 specifies the action (render a page in a headless Chromium browser with JavaScript execution) and the outcome (extract main content as clean markdown). It distinguishes itself from plain fetching and screenshot, and the siblings (web.*) are not confused because it explicitly says when to use this over 'cheaper extract' and 'screenshot' for pixel evidence.

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?

It explicitly states when to use (SPAs and JS-heavy sites where plain fetching returns an empty shell), when not to use (static pages – try the cheaper extract first), and provides an alternative for a different need (screenshot for pixel evidence). This is clear, actionable guidance that prevents misuse.

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