MCP Scrcpy Vision

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

No annotations are provided, so the description carries the full burden. It discloses the action ('Turns off the screen') and method ('using KEYCODE_SLEEP'), but lacks critical behavioral details: it doesn't mention if this requires device permissions, whether it's reversible (e.g., via android.screen.wake), potential side effects (e.g., locking the device), or error conditions (e.g., if the device is already asleep). For a mutation tool with zero annotation coverage, this is insufficient.

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, consisting of two clear sentences that directly state the action and method. Every word earns its place, with no redundancy or unnecessary details, making it easy for an agent 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 the tool's complexity (a mutation action with no annotations and no output schema), the description is incomplete. It lacks information on prerequisites (e.g., device connectivity), behavioral outcomes (e.g., what happens after sleep), error handling, and how it integrates with sibling tools like android.screen.wake. For a tool that changes device state, more context is needed to ensure safe and correct usage.

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 description adds no information about the 'serial' parameter beyond what the input schema provides (a required string). With 0% schema description coverage and 1 parameter, the description does not compensate by explaining what 'serial' represents (e.g., device identifier) or its format. However, since there's only one parameter and the tool's purpose is straightforward, the baseline is 3, indicating minimal but adequate coverage given the simplicity.

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 ('Puts to sleep') and resource ('device screen'), and mentions the specific mechanism ('using KEYCODE_SLEEP (223)'). It distinguishes from siblings like android.screen.wake (opposite action) and android.screen.isOn (status check), though not explicitly named. However, it doesn't fully differentiate from all screen-related tools like android.screen.unlock, which might have overlapping use cases.

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 explicit guidance on when to use this tool versus alternatives is provided. The description implies usage for turning off the screen, but it doesn't specify scenarios (e.g., to save battery, during idle periods) or contrast with other tools like android.screen.unlock (which might involve screen state changes) or android.screen.wake (the inverse action). This leaves the agent to infer usage from context alone.

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