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

With no annotations, the description carries the full burden. It reveals that parsing happens in-Worker with no upstream service, describes exactly what each format returns, and explains the payment behavior including the required x_payment payload and the pricing tool shortcut. This is exceptionally transparent.

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 description is three sentences, each earning its place: the purpose and size limit, the format behaviors, and the payment workflow. It is front-loaded with the core action and not a single redundant word.

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?

Given no output schema, the description fully covers return values for both formats. It also addresses the payment flow, size limitation, and processing location, making it complete for a tool of this complexity (3 params, payment gate).

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 schema already covers 100% of parameters, so baseline is 3. The description adds meaningful semantics for 'format' by specifying that text returns 'one clean plain-text string' and json returns 'per-page text array plus document metadata.' It also clarifies the x_payment usage context. This exceeds the baseline.

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 'Extract any PDF up to 10 MB by URL,' a specific verb+resource statement that clearly differentiates this from sibling tools like image_to_text or read_url. It also explains the two format options, making the tool's purpose unambiguous.

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 gives clear context by specifying the file size limit and the exact two-step payment workflow (call without x_payment, then sign and call again). While it doesn't explicitly say 'use this instead of X,' the tool's purpose and the mention of the 'pricing' tool provide adequate usage guidance. Missing explicit alternatives, hence 4 rather than 5.

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