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

With no annotations, the description carries the full burden and does meaningful work: it discloses the invisible-text-layer side effect, the 100-page cap, and the cost model ('1,25 ₽ за каждые 10 страниц'). It omits error/permission behavior, but the operational traits it does disclose are exactly the ones an agent needs.

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?

Purpose is front-loaded, followed by limits/cost and then per-parameter notes. Every sentence contributes; the only slight inefficiency is splitting parameter hints into a trailing block rather than integrating them 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, and the description supplies limits, pricing, the large-file workflow, and both parameter meanings. It leaves auth/error conditions unstated, which is a modest gap for a paid conversion tool.

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 document both parameters, and it does: file_url is described as a public PDF URL and languages is described with an example and a default ('русский + английский'). Minor gap is that 'public URL' accessibility constraints are not spelled out.

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+resource ('Распознаёт текст в сканированном PDF (OCR)') and adds the concrete effect ('Добавляет невидимый текстовый слой'), which separates OCR from the extraction siblings like pdf_to_txt. An agent can identify the operation without opening the 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 clear context (scanned PDFs), an explicit size boundary ('До 100 страниц за раз') and names the alternative for overflow ('больший файл сначала разделите split_pdf'). It stops short of any when-not guidance versus related convert/extract tools, so it is strong but not exhaustive.

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