Hold/Release Key

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

Beyond the annotations (readOnlyHint=false, destructiveHint=false), the description discloses important behavioral traits: auto-release after 30 seconds as a safety net, release on helper shutdown, and the requirement for Accessibility permission. This adds meaningful context not present in annotations.

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?

Two sentences, no fluff. The first sentence states the function and use case; the second conveys safety and permission. Every sentence earns its place and the structure is front-loaded with the primary action.

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?

For a simple two-parameter tool with no output schema, the description covers purpose, usage context, behavioral safety net, and prerequisites. No significant gaps remain for an agent to correctly select and invoke the 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 schema describes 'key' but not 'action'; the description fills that gap by explaining action values ('down'/'up') and provides a practical example ('shift') that aids understanding. With 50% schema coverage, the description compensates well without redundancy.

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 uses specific verbs 'Hold' and 'release' with a clear resource ('a single key') and explains the action parameter values (down/up). It distinguishes itself from siblings like input_press_keys by explicitly targeting gesture-like sequences, making the purpose unmistakable.

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 a concrete use case ('holding shift while clicking multiple items'), clearly implying when to use this tool. It does not explicitly name alternative tools or exclusions, but the example gives sufficient context to differentiate from other input tools.

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