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

Annotations already indicate read-only, idempotent, and non-destructive behavior. The description adds useful context by specifying the watermark type (invisible DCT) and the return payload, which are not captured in the annotations. It does not contradict the annotations, and the 'FREE' repetition is noise but not misleading.

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 core description is succinct and front-loaded with the key purpose. However, the repeated 'FREE. (FREE)' is redundant and does not earn its place, reducing the overall conciseness score.

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 simple one-parameter read-only tool with strong annotations, the description covers purpose, method, and return value. It could mention failure behavior when no watermark is found, but the current wording is sufficient for basic invocation. The absence of an output schema is mitigated by the explicit return description.

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 coverage is 100% (single 'image' parameter with a clear description). The tool description does not add parameter-specific details beyond the schema, so it meets the baseline without adding extra semantic value.

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's function: detect and extract an invisible DCT watermark from an image, with a specific output (embedded text payload). It distinguishes itself from sibling watermark_embed by focusing on detection rather than embedding.

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 for extracting a watermark but does not explicitly state when to prefer this tool over alternatives (e.g., watermark_embed). No exclusions or alternative tool mentions are provided, making the guidance implicit rather than explicit.

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