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

Annotations indicate the tool is not read-only (mutation expected) and not idempotent, but the description adds no extra behavioral context. It does not disclose whether the operation is asynchronous, whether it returns a URL, or any side effects (e.g., creates a new file). The 'hyper-realistic effect' claim is a quality statement, not a behavioral disclosure.

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 two sentences that redundantly restate the same idea: both mention face swapping with multiple faces. It wastes words on marketing filler ('we've got you covered') and does not front-load the essential action. A single clear sentence would be more effective.

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?

This is a complex tool with four request variants, polling behavior, and face mapping logic. The description does not explain the overall workflow, the need for source and reference images, or the output format. Despite the rich schema, the description completely fails to provide a conceptual overview, making it inadequate for an agent to understand how to invoke the tool correctly.

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 description does not mention any parameters or explain the request structure. Although the schema provides detailed descriptions for 'face_mapping' and 'src_file_url', coverage is only 50%, and the description fails to compensate for undocumented parameters like 'ref_file_urls' and 'ref_file_ids'. It adds no value beyond the schema.

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 states the tool swaps faces ('swapping one or multiple faces'), so the core action is clear. However, it doesn't specify the domain (image vs. video) and uses vague marketing language ('hyper-realistic effect'). It also fails to distinguish from the sibling tool 'AI-Video-Face-Swap', making the purpose somewhat ambiguous.

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 provides no guidance on when to use this tool over alternatives. Phrases like 'creating funny pictures of faces' or 'need a professional tool' are not actionable usage criteria. There is no mention of prerequisites (e.g., source image, reference images) or exclusions (e.g., video face swap).

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