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

Annotations already cover read-only, open-world, idempotent and non-destructive, and the description adds substantial behavior beyond them: it follows redirects safely, refuses non-text content, caps payloads at 2 MB, requires no API key, and documents the payment model ($0.002/call via x402, prepaid x-credit-token header for unlimited, 1 free call/day). That is exactly the kind of auth, limit and cost context annotations cannot express.

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 core purpose is front-loaded, which is good, but the paragraph is padded with marketing filler ('The step every agent needs', 'Nothing crypto about it') and a redundant 'Required input: url' sentence the schema already covers. The pricing and auth sentences earn their place; the rest dilutes them.

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?

An output schema exists so return values need not be explained, yet the description helpfully previews them. With redirect handling, content-type refusal, a size cap and the full payment/auth model disclosed, an agent has nearly everything needed to call it correctly; only explicit sibling differentiation is missing.

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 only two parameters, so the schema already carries the load and baseline is 3. The description restates the required input (url) but adds nothing about the optional maxChars parameter or the URL format beyond what the schema provides.

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: pass a URL, get back clean agent-ready text with nav/scripts/ads stripped plus title, description and site name. It is precise about the transformation. It does not, however, differentiate itself from close siblings like web_extract, url_to_json or exa_contents, which an agent would need in order to choose between them.

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 gives clear context for when to reach for it: before reasoning about a page, and specifically for serverless/MCP runtimes that have no browser or HTML parser. That is a real usage signal. But it never names an alternative tool or states when NOT to use it, so selection against url_to_json/web_extract is left to inference.

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