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

Annotations already declare readOnlyHint and openWorldHint, so the description only needs to add context. It adds useful behavioral details: output includes clean Markdown plus metadata fields, pricing via x402, and that failed reads are not charged. No annotation contradiction exists.

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?

Two sentences deliver purpose, output contents, pricing, and failure billing without wasted words. The core function is front-loaded, and pricing/failure policy is placed as a compact second sentence.

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 adequately names the return payload (Markdown plus title, author, date, JSON-LD, links) and notes cost/failure behavior. It could mention error handling or redirect behavior, but for a read-only fetch tool the provided context is sufficient for a likely-correct call.

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 the schema already explains url, selector, and max_chars. The description does not need to restate parameters and adds no extra per-parameter semantics, landing at the baseline for fully documented schemas.

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 states a specific verb ('Fetch') and resource ('a public web page or PDF') and clearly promises clean Markdown plus title, author, date, JSON-LD, and links. This differentiates it from the metadata-only sibling get_page_metadata and from the x402 service-check siblings.

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 makes clear this tool is for public web pages/PDFs and that failed reads are not charged, giving an agent a good sense of when it applies. It does not explicitly name alternative tools or exclusion conditions, but the context is clear enough for selection.

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