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

With no annotations, the description carries the full burden and does well: it discloses the non-destructive semantics ('содержимое за краем остаётся в файле') and the default behavior when box is absent. It does not mention permission/auth requirements, rate limits, or whether the output is a new file vs in-place edit.

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?

Front-loaded with the core action and default, then one line per parameter. Efficient and scannable; the box example is worth its length, though the redact_pdf aside could be folded more tightly.

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?

An output schema exists, so return values need no explanation. Given a 3-param mutation tool with no annotations, the description covers defaults, coordinate semantics, and the destructive-vs-non-destructive distinction well; only auth/permission context and output-format expectations are unaddressed.

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 0%, so the description must supply all meaning — and it does: file_url is a public URL, box is [x0,y0,x1,y1] in 0–1 fractions of the visible page with top-left origin and a concrete example, and pages is 1-based numbers or 'all'. This fully compensates for the empty schema descriptions.

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?

States a specific verb and resource ('Обрезает страницы PDF') and immediately defines the default mode ('без box — убирает белые поля автоматически'). It also names the sibling it is not (redact_pdf) for the data-hiding case, so an agent can distinguish it from the ~50 siblings without opening a schema.

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?

Gives an explicit when-to-use branch: omit 'box' to auto-trim white margins, supply 'box' for a specific region. It also names an explicit when-not and the correct alternative — 'для скрытия данных используйте redact_pdf' — which is the most likely misuse of a crop tool.

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