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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is fully carried by structured data. The description adds two non-obvious facts not in annotations: no wallet/payment is required and no arguments are needed. That is real added value, but it stops there.

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?

One tight sentence, front-loaded with [FREE] and the payment/error-proofing facts. Nothing 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?

For a zero-param preview tool this is adequate: it tells you it costs nothing and takes no inputs. But it never states what the real pdf_extract actually extracts, so an agent cannot fully judge whether this sample is worth invoking.

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?

Zero parameters, so baseline is 4. The description explicitly states 'no arguments needed,' which correctly and usefully reinforces the empty schema.

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 this is a free sample/preview of pdf_extract, so the resource is clear and the sibling relationship is explicit. But it never says what the tool actually does (PDF text extraction), only that it mirrors pdf_extract. A reader who did not recognize the name would not know the purpose from this sentence.

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 implies the usage condition (free preview before paying for pdf_extract), but gives no explicit when-to-use vs. when-to-use-pdf_extract guidance beyond 'sample response.'

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