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 describes the action (tap) and target (back button), but doesn't disclose behavioral traits like whether this requires the app to be in a navigable state, what happens if no back button is present, or if there are any side effects. The description adds basic context but lacks richer behavioral details.

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 that immediately states the action and target. Every word earns its place with no redundancy or unnecessary elaboration. It's appropriately sized and front-loaded.

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 (0 parameters, no annotations, but has output schema), the description is reasonably complete. It explains what the tool does, though it could benefit from more behavioral context. The output schema existence means the description doesn't need to explain return values, making it adequate for this low-complexity 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?

The tool has 0 parameters with 100% schema description coverage. The description doesn't need to explain parameters, and it appropriately doesn't mention any. Baseline for 0 parameters is 4, as there's no parameter information to add 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 specific action ('Tap') and the target resource ('iOS navigation back button') with precise location ('top-left corner'). It distinguishes from siblings like 'go_home' or 'tap' by specifying the exact UI element to interact with.

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 (when navigating iOS apps) but doesn't explicitly state when to use this tool versus alternatives like 'go_home' or 'swipe_to_previous_page'. It provides clear context about the target element but lacks explicit exclusions or named alternatives.

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