vphone-mcp

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

No annotations are provided, so the description carries full burden. It states the action but doesn't disclose behavioral traits: it doesn't specify if this is a short press or long press, whether it requires device permissions, what happens on different device states (on/off/locked), or potential side effects (e.g., triggering biometric authentication). For a zero-parameter tool with no annotation coverage, this leaves critical behavior ambiguous.

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, efficient sentence with a parenthetical clarification that adds necessary context ('lock/wake'). It's front-loaded with the core action and wastes no words. Every part earns its place, making it highly concise and well-structured.

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 simplicity (zero parameters, no annotations, but with an output schema), the description is minimally adequate. It states what the tool does but lacks context on usage, behavior, or output. The output schema existence means return values needn't be explained, but for a power button action that could have varied effects, more guidance would improve 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?

The tool has zero parameters, and schema description coverage is 100% (though trivial since there are no parameters). The description doesn't need to explain parameters, so it meets the baseline of 4 for zero-parameter tools. No additional parameter semantics are required or provided.

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 action ('Press') and target ('power button') with a parenthetical clarification of its function ('lock/wake'). It distinguishes from siblings like volume_up/down or tap by specifying the power button. However, it doesn't explicitly differentiate from all other button/control tools, keeping it from a perfect 5.

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 versus alternatives. It doesn't mention scenarios for pressing the power button (e.g., waking a locked device, putting to sleep) or warn against misuse (e.g., holding too long for shutdown). With siblings like go_home or open_control_center that might serve similar wake/lock purposes in some contexts, this lack of differentiation is a significant gap.

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