is_user_present

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

With no annotations provided, the description conveys key behavioral traits: it uses the webcam for face detection, returns a structured JSON with a 'present' field and an explanatory message, and handles camera access errors by returning an error message. This is detailed for a simple read-only check, though it does not mention potential privacy implications or permission requirements.

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, consisting of two short paragraphs and only three sentences. Every sentence contributes essential information: what the tool does, what it returns, and its error behavior. There is no redundancy or filler, making it well-structured and efficient.

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 simplicity of the tool (no parameters, no annotations, no output schema), the description covers the essential aspects: the action, the return format, and error handling. It is sufficiently complete for an agent to understand and invoke the tool correctly. Minor additional details like a note on webcam privacy could improve it, but they are not necessary for basic operation.

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 tool has zero parameters, and the rubric sets a baseline of 4 for such cases. The description correctly omits parameter details since there are none, and it does not need to compensate for schema gaps. The description simply adds meaningful context about the tool's operation without needing to explain parameters.

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 purpose: 'Check if the user is sitting at their computer by detecting a face via the webcam.' It includes a specific verb ('check'), a resource ('user presence'), and the method ('detecting a face via webcam'), making it distinct and unambiguous. Although no siblings are listed, the description would differentiate from any related tool by specifying the face-detection approach.

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 gives clear context by explaining that the tool detects user presence via webcam, which implies when it should be used. It also notes error behavior when the camera is inaccessible, providing an implicit caveat. However, it does not explicitly state scenarios where this tool should be avoided or alternatives, but with no sibling tools, that is not a major gap.

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