add_watermark

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

No annotations are provided, so the description must disclose behavioral traits. It only states the action and doesn't mention output behavior, side effects, or handling of input/output files. The schema provides parameter details but not tool-level behavior.

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, front-loaded sentence with no redundant words. It immediately conveys the tool's function and is appropriately sized for the simplicity of the action.

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?

Despite the detailed schema, the description lacks any context about the workflow (input→output), return value, or caveats. With no output schema and no annotations, the agent does not know what the tool returns or whether it modifies the input image. This is a meaningful gap for a 14-parameter 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?

The schema already describes all 14 parameters thoroughly (100% coverage) with types, defaults, and enums. The description adds no parameter-specific information, so the baseline of 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 clearly states the tool adds a watermark (image or text) to an image, using a specific verb and resource. This distinguishes it from sibling tools like optimize_image or auto_crop.

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 (when you need to add a watermark) but offers no explicit guidance on when to prefer this tool over alternatives, no exclusions, and no prerequisites. Sibling tools are clearly different, but the description does not name alternatives.

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