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

Annotations already declare readOnlyHint=false (modifies), idempotentHint=true, and destructiveHint=false. The description adds no additional behavioral context such as file output details or side effects. It does not contradict annotations, but also does not enrich them, so a neutral score is appropriate.

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 sentence with zero waste, directly stating the action and target. It is front-loaded and earns its place without redundancy.

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 simple tool with full schema documentation and an output schema present, the description is sufficient. It doesn't explain return behavior, but the output schema covers that. Minor gap: no mention of whether it creates a new file or modifies in-place, but annotations imply modification and the operation is straightforward.

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?

Schema coverage is 100% with detailed descriptions for each parameter (position lists options, start_number explains default). The description itself adds no parameter-level detail, and the schema already fully documents them, so baseline 3 is justified.

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 'Add page numbers to a PDF' uses a specific verb and resource, clearly distinguishing it from sibling tools like compress_pdf, extract_pages, etc., which have distinct purposes. The intent 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?

No explicit guidance on when to use this tool vs alternatives is provided. However, the name and description make the usage context obvious, so usage is implied rather than explicitly stated. It lacks any 'when not to use' or alternative references.

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