MCP Scrcpy Vision

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

With no annotations provided, the description carries the full burden. It discloses the fallback behavior between scrcpy and adb protocols, which is useful context for performance or reliability. However, it lacks details on error handling, permissions required, or what happens if coordinates are out of bounds, leaving gaps for a mutation tool.

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 front-loaded with the core action and efficiently adds technical details in a single, well-structured sentence. Every part earns its place without redundancy, making it easy to parse quickly.

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 no annotations, no output schema, and 4 parameters with 0% schema coverage, the description is moderately complete. It covers the basic action and fallback mechanism but lacks details on return values, error cases, or full parameter explanations, which could hinder safe usage in complex scenarios.

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 0%, so the description must compensate. It mentions coordinates (x,y) and duration, mapping to parameters x, y, and durationMs, but doesn't explain the serial parameter (device identifier) or provide units/constraints beyond the schema. This adds some meaning but is incomplete for all 4 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 action ('Performs a long press') and the target ('at coordinates (x,y) on the device screen'), distinguishing it from siblings like android.input.tap (brief press) and android.input.swipe (drag gesture). However, it doesn't explicitly differentiate from android.input.dragDrop, which might also involve long presses as part of drag operations.

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 by mentioning the fallback mechanism ('Uses fast scrcpy control protocol when stream is active, otherwise falls back to adb shell input'), which suggests context about performance or availability. However, it doesn't provide explicit guidance on when to use this tool versus alternatives like android.input.tap for short presses or android.input.dragDrop for drag operations, nor does it specify prerequisites or exclusions.

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