pdf_add_watermark

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

While annotations cover safety (destructiveHint: false, idempotentHint: true), the description adds valuable behavioral context not found elsewhere: the watermark is 'centered' and visually 'rotated diagonally' (explaining the 45-degree default), and clarifies the default page scope. It does not contradict annotations.

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 sentences efficiently structured: purpose statement first, followed by visual layout defaults, then scope defaults. Every sentence conveys information not replicated in the structured fields, with no redundant or wasted words.

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?

Given the rich schema (8 parameters, 100% coverage) and clear annotations, the description provides appropriate context for defaults and visual appearance. It could explicitly mention that the source file remains unmodified (implied by outputPath requirement and destructiveHint), but is otherwise complete for the tool's complexity.

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?

With 100% schema coverage, the baseline is 3. The description adds semantic value beyond the schema by explaining that diagonal rotation means 45 degrees and explicitly stating that omission of the page range results in all pages being watermarked. It also notes the watermark is 'centered,' which is not documented in any parameter description.

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 opens with a clear specific verb ('Add') and resource ('text watermark to PDF pages'), immediately distinguishing it from sibling tools like pdf_add_page_numbers or pdf_encrypt. It precisely defines the tool's scope.

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?

The description implies usage patterns by explaining default behaviors (applies to all pages if no range specified, diagonal rotation), but lacks explicit guidance on when to use this versus alternatives like pdf_embed_image or prerequisites for the operation.

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