Count pages in several PDFs

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

With no annotations, the description carries the behavioral disclosure burden. It explicitly states the operation is read-only, describes how unreadable files are handled (reported on their own row without blocking others), and notes the service is free and unlimited. This gives an agent a solid behavioral model even without annotations.

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 compact and front-loaded: it opens with the core result, then covers failure behavior, then the safety and pricing traits. Every sentence adds information, and there is no filler or repetition.

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, low-complexity tool, the description covers the essential operational details: per-file counts, total, readable count, and behavior on unreadable files. It does not specify the exact return format, but no output schema exists and the described behavior is sufficient for an agent to predict the result 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?

The schema already covers the single parameter fully with the description 'Paths to the PDF files'. The tool description reinforces that any number of PDFs is supported but does not add new semantic details about path format or file handling, so the baseline 3 is appropriate.

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 uses a specific verb and resource: counting pages in PDFs, and specifies the exact outputs: per-file page count, total, and readable count. It does not explicitly differentiate this tool from sibling tools like pdf_pages or pdf_info, but the batch and aggregate behavior is clear enough that the purpose is 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 implies when to use it: when you need page counts for many PDFs at once, including a total and resilience to unreadable files. However, it does not name alternatives such as pdf_pages or pdf_info, nor state when not to use this tool, so the usage guidance remains implicit rather than explicit.

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