vphone-mcp

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool captures and returns an image, implying a read-only operation without side effects, but lacks details on permissions, rate limits, or error conditions. It adds some context (e.g., 'embedded image that can be analyzed visually') but is not comprehensive for a tool with potential behavioral nuances.

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 highly concise and front-loaded, with two sentences that directly state the action and output. Every sentence earns its place by clarifying the tool's function and return format, with no wasted words or unnecessary elaboration.

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's low complexity (0 parameters, no output schema, no annotations), the description is reasonably complete. It covers the core purpose and output format adequately. However, it could improve by addressing behavioral aspects like error handling or usage constraints, which are relevant even for simple tools.

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 input schema has 0 parameters with 100% coverage, so no parameter documentation is needed. The description does not add parameter semantics beyond the schema, but since there are no parameters, a baseline score of 4 is appropriate as it avoids redundancy and focuses on the tool's purpose.

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 specific action ('Take a screenshot') and resource ('of the VM display'), distinguishing it from sibling tools that perform UI interactions like tapping, scrolling, or opening apps. It precisely defines the tool's function without being vague or tautological.

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 context by specifying 'of the VM display,' suggesting it captures the current visual state of a virtual machine. However, it does not explicitly state when to use this tool versus alternatives (e.g., for visual analysis vs. other UI actions), nor does it provide exclusions or prerequisites, leaving some guidance gaps.

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