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

With no annotations, the description carries the full disclosure burden and does so well: it explains fallback behavior (OCR, headless Chrome), the paid-call flow ($0.001 USDC on Base, HTTP 402 + PAYMENT-SIGNATURE retry), that failed fetches are not charged, and the OCR page cap. These are exactly the non-obvious traits an agent needs before invoking.

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?

Dense but front-loaded and well-parenthesized; the core purpose leads and payment constraints follow. It is long, but nearly every clause (pricing, 402 retry, free failures, deep alternative) carries operational weight, so little is wasted.

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-shape explanation is a bonus rather than a requirement, and the description still names the returned fields. Combined with the auth/payment model, fallback behavior and endpoint alternatives, an agent has everything needed to call it correctly.

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?

At 57% schema coverage the description compensates meaningfully: it clarifies what the format options yield (clean markdown vs text/html), explains the OCR auto behavior, and adds the OCR first-3-pages limit that isn't in the schema. max_chars, include_links and ocr_lang still get no descriptive coverage anywhere, so it falls short of full compensation.

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?

Opens with a specific verb+resource ("fetch a public URL and return the main content as clean markdown") and names the outputs (title, lang, dir, word_count, sha256). An agent immediately knows this is a page-fetching/extraction tool, distinct from the pricing/VAT/verification 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?

Gives clear operating conditions: OCR auto-triggers for scanned PDFs or garbled text layers, headless Chrome is used for JS-rendered pages, robots.txt is respected, and it names an alternative endpoint (/v1/read/deep) for 10-page OCR. It does not state when NOT to use the tool or contrast it with the siblings, but the context is otherwise unambiguous.

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