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

Annotations already declare readOnly=true, destructive=false, idempotent=false and openWorld=true, so the safety bar is low. The description nonetheless adds cost details ('$0.01/call via x402 USDC or a card key', 'failed calls free', 'repeats are not free'), which explains why idempotency is false, and describes what happens internally (navigation and boilerplate stripped before summarizing).

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 opening sentence front-loads the output shape and the next explains the mechanism, so an agent gets the gist immediately. The closing stack of pricing and 'changes nothing' reminders is a touch repetitive with the annotations, but every sentence still carries information.

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?

For a one-parameter tool with no output schema, the description supplies the return shape ('short summary ... plus three to six key points'), the failure/compatibility boundary (HTML only), pricing, and the sibling handoffs. Nothing needed to invoke it correctly 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?

The single parameter has 100% schema coverage, including 'Absolute http(s) URL', so the schema already carries the meaning. The description adds only a concrete example URL and the 'Give a URL' framing, which is helpful but not substantially beyond the schema. Baseline 3 fits.

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 and resource ('fetches the page ... summarizes the main text with an LLM') and immediately names what it is not: 'HTML pages only; for a PDF use pdf_text' and 'For the full text use extract.' An agent can separate it from extract, contents, pdf_text and page_publish without opening a 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?

Gives explicit use cases ('research, news triage, link previews and deciding whether a page is worth reading in full') plus an exclusion with a named alternative for PDFs and for full text. It also warns that repeats are not free because each call is charged.

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