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

Beyond the annotations (readOnly/openWorld/idempotent/non-destructive), it discloses cleanup behavior (menus, ads and footers removed), the exact return payload keys, specific error codes and their meanings, and a per-call price of $0.003 USDC via x402. This is exactly the kind of behavioral detail annotations cannot carry.

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?

Front-loaded with what it does and what it returns, then usage guidance, then output shape, errors and price. Every sentence carries distinct information; no 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?

With no output schema, the description compensates by enumerating the returned JSON fields and enumerating failure modes (400/422/502) plus cost. An agent has everything needed to invoke it and interpret results.

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?

Only one parameter with 100% schema description coverage, and the schema already states "http/https, public". The description reinforces the public-URL constraint (400 for bad or private URL) but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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?

States a specific verb (fetch) and resource (public web page) plus the exact transformation and output (main article as clean Markdown with title, byline, excerpt). This clearly separates it from siblings like screenshot_webpage, html_to_pdf and convert_file, which operate on other formats or produce other artifacts.

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?

"Use when you need to read, summarise or quote a web page cheaply without parsing HTML yourself" gives a clear positive trigger and implicitly contrasts with HTML-parsing alternatives. It stops short of explicitly naming sibling tools or stating when-not to use it (e.g. vs. screenshot_webpage for JS-heavy or paywalled pages).

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