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

Beyond the readOnlyHint/openWorldHint annotations, it discloses the transport mechanics (plain HTTP, no JS rendering, 15 s timeout, first 2 MB only), the failure contract (isError with reason, never charged), and the full payment model including the x402 flow and the free daily quota. This is unusually rich operational context the annotations cannot convey.

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?

It is dense and long, but front-loaded (purpose, then routing, then mechanics, then cost) and every clause carries distinct information. Slightly run-on in the pricing sentence, but 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 fields directly, and it covers limits, error behavior, and billing. An agent has everything needed to call it correctly and to anticipate cost and failure modes.

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%, so both parameters (url, payment) are already documented in the schema, including how to obtain the price when payment is omitted. The description adds pricing/quota context but no new meaning about the parameter values themselves, so the baseline 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 opens with a specific verb and resource ('Fetch a public web page and return its metadata') and enumerates exactly what is returned (title, description, canonical URL, language, OG/Twitter tags, icons, JSON-LD). It explicitly contrasts itself with the sibling page_to_markdown, so an agent can distinguish it without opening either schema.

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 names concrete use cases ('link previews, SEO checks or structured data without the page body') and gives an explicit routing rule: 'use page_to_markdown when you need the readable text and links.' This is a clear when/when-not/alternative statement.

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