detect_faces

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

No annotations provided, so the description carries full burden. It discloses offline operation, no API key needed, and return format (JSON with count and positions as percentages). However, it omits details like supported file types, what happens if no faces found, or error handling. Still covers core behavioral traits well.

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 extremely concise with two short paragraphs. The first sentence states the core function, followed by explicit usage guidelines and return format. Every sentence adds value with no wasted words.

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 no output schema, the description adequately explains the return format (face count and positions). It differentiates from siblings. However, it could mention supported image file types or behavior when no faces are detected. Overall complete for a simple 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?

Schema coverage is 100% for the single 'path' parameter, so the baseline is 3. The description adds little beyond the schema, just reiterating 'local image file' and 'absolute or relative path'. No additional semantic value or constraints beyond what the schema already provides.

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 detects human faces in a local image using Apple Vision, with a specific verb and resource. It distinguishes from siblings by listing what not to use it for (text extraction, barcode reading) and naming alternative tools.

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?

Explicit USE WHEN condition (user wants face count/positions) and DO NOT USE with specific alternatives (ocr_image, detect_barcodes) are provided, giving clear guidance on when to invoke this tool versus siblings.

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