boxes.screenshot

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

With no annotations, the description carries the full burden of behavioral disclosure. It does add a key constraint: the VM must be 'running' to capture a screenshot. It also states the output format ('as MCP image content'), which is useful. However, it omits details like whether the operation is read-only, any resolution limits, or side effects. Given the minimal but relevant information, a score of 3 is appropriate.

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 a single, well-formed sentence that delivers the core purpose without any fluff. It is appropriately concise and front-loaded, 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 the tool has 3 parameters, no output schema, and no annotations, the description is too sparse. It does not explain the 'screen' parameter (which screen index), the 'backend' parameter (what options mean, when to choose one), or the nature of the returned image content beyond a generic 'MCP image content'. An agent would struggle to use screen/backend correctly, and the lack of any output detail further limits completeness.

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 description coverage is only 33% (only nameOrUuid has a description in the schema). The description does not explain the meaning or usage of 'screen' or 'backend' at all, nor does it clarify the expected values or defaults. Since the description fails to compensate for the low schema coverage, this dimension scores low – the tool cannot be invoked correctly without additional knowledge of these 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 verb ('Capture') and resource ('running VM display screenshot') and specifies the output type ('as MCP image content'). It is specific enough for an agent to understand the tool's function, though it does not explicitly differentiate from the sibling boxes.display, which could also capture display-related data. This slight ambiguity prevents a perfect score.

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?

No guidance is provided on when to use this tool versus alternatives like boxes.display. There is no mention of preconditions beyond 'running VM' (which is more a behavioral requirement than usage guidance). The description does not state when not to use it or what makes it the right choice among siblings.

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