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

It discloses the diagonal placement and configurable opacity/angle, which goes beyond the basic annotations. However, it does not state whether the original file is modified or whether a new output file is produced; with no output schema, that behavioral gap remains.

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?

A single sentence that front-loads the purpose and key controls without any filler. Every clause contributes useful information for tool selection.

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 100% schema coverage and clear purpose, the description is largely sufficient for an agent to call the tool correctly. It does not explain output/return behavior, but the schema already names output_filename and the overall intent is unambiguous.

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 100%, so the parameters are already well documented. The description adds no meaning beyond mentioning opacity and angle, which aligns with the schema; baseline 3 is appropriate.

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 uses a specific verb ('stamp') and a clear resource ('text ... across PDF pages'), with concrete examples like 'CONFIDENTIAL' or 'DRAFT'. This clearly distinguishes it from sibling tools such as add_page_numbers or compress_pdf.

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 the tool is for adding text watermarks to PDFs, and the examples suggest common use cases. However, it does not explicitly state when to prefer this tool over alternatives or mention any exclusions, so usage guidance is only implied.

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