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

With no annotations, the description carries full responsibility for behavioral disclosure, but it only notes 'Browser-based tool.' It doesn't reveal whether it creates a new PDF, modifies in place, how it handles uploads, file size limits, or whether numbers are applied to all pages. This is a significant gap.

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 a single, front-loaded sentence with no redundant text. It efficiently communicates the primary action and adds the 'browser-based' context, making it concise and well-structured.

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?

Despite the tool's low complexity, the description is too sparse. It doesn't clarify the exact functionality (page numbers) in the description, lacks any behavioral context, and doesn't distinguish from many sibling PDF tools. With no output schema or annotations, this is insufficient for an agent to accurately predict behavior.

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 tool has zero parameters, so the input schema provides complete coverage. Per the rules, the baseline for zero parameters is 4, and the description adds no parameter-specific information, which is acceptable here.

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 the core action 'PDFに番号を振る' (add numbers to PDF), and the title clarifies it as adding PDF page numbers. This gives a clear verb+resource pairing, though the description itself doesn't explicitly say 'page numbers,' relying on the title for that distinction.

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?

No guidance is provided on when to use this tool or how it differs from alternatives like pdf-stamper or pdf-edit. There are no use cases, prerequisites, or exclusions mentioned, leaving the agent without direction.

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