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

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds only "Returns the result file" and says nothing about whether the source document is preserved, how the crop margins are measured, or whether pages are selectively processed.

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?

Three short sentences with the core action front-loaded and no filler. It is efficient, though the choppy fragments ("Accepts pdf.") could have carried more substance at the same length.

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?

With a nested options object, a free-form page-selection string, and no output schema, the description should explain margin units, page-range syntax, and what the returned file is. None of that is present, so an agent must guess at the core geometry semantics.

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 description coverage is high, so the baseline is 3. However the four margin integers carry no unit or meaning in either schema or description, and the free-form "pages" string has no documented syntax, so the description does not compensate for those real semantic gaps.

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?

"Cut margins off PDF pages" names a specific verb and resource, and the crop operation is distinguishable from siblings like compress-pdf or rotate-pdf by name alone. It stops short of explicitly contrasting with those siblings, but 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?

There is no guidance on when to choose this over compress-pdf, pdf-to-image, or other page-geometry siblings, and no prerequisites or exclusions are stated. "Accepts pdf" is an input constraint, not usage guidance.

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