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

No annotations are provided, so the description carries the full behavioral burden. It implies an additive write, but never states whether the watermark overwrites existing content, whether it is reversible, what permissions or file-state conditions apply, or any rate limits. Output schema exists so return format need not be covered, but the mutation/authorization profile is absent.

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 in one sentence, followed by a tight parameter reference. No filler, no repetition. It is dense but readable, with each line earning its place.

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 mutation tool with no annotations, the definition is only adequate: it covers inputs thoroughly but omits any behavioral/operational context (destructiveness, prerequisites, error conditions). The existing output schema relieves it of explaining return values, which keeps this from being lower.

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 0%, so the description must compensate fully — and it does. Every parameter is documented with meaning, defaults ('по умолчанию 0.3', 45), value ranges (0.0–1.0), the enumerated position options, and the text/image_url mutual exclusion.

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 ('adds a watermark to PDF pages'), which clearly distinguishes it from siblings like add_page_numbers, protect_pdf, and flatten_pdf. It's clear and unambiguous, though it never explicitly names an alternative tool to route away from.

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 explicit when-to-use or when-not-to-use guidance. The one piece of usage context provided is the mutual exclusivity between 'text' and 'image_url' ('excludes image_url' / 'excludes text'), which is useful but is a parameter constraint rather than selection guidance.

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