apply_watermark

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

No annotations are provided, so the description bears the full burden of behavioral disclosure. It states that a watermark is applied, but does not disclose whether the original image is modified, what happens when both text and logo_path are supplied, what image formats are supported, or how output files are handled. Key behavioral details beyond the schema are missing.

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?

The description is a single sentence with no filler, and it front-loads the purpose before mentioning customizations. It is appropriately short for a well-schematized tool, though the phrase 'and styling' is slightly vague relative to the rich parameter set.

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 tool has 9 parameters, no annotations, and no output schema, this high-level description is not sufficient for an agent to fully understand call behavior. It does not explain critical interaction rules such as whether text and logo can be combined, whether tile mode requires special handling, or what side effects occur on the filesystem.

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 baseline is 3. The description does add a high-level gloss by mentioning text or logo watermarks and customizable placement, opacity, and styling, but it does not provide deeper meaning or clarify ambiguous parameter interactions beyond what the schema already documents.

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 clear verb-resource structure: 'Protect product photos, artwork, and marketing images by applying a text or logo watermark.' This unambiguously distinguishes it from siblings strip_photo_metadata and resize_for_platform, which serve different purposes. The scope of the operation is immediately apparent.

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 should be used when an image needs protection via a watermark, and the sibling tools have obviously different functions. However, it never explicitly states when to use this tool versus alternatives, nor does it mention any exclusions or conditions where one of the sibling tools would be more appropriate.

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