key_down

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

With no annotations, the description carries the full behavioral burden and does disclose the key trait: the key remains held until explicitly released. It also explains the two release paths, though it omits focus requirements, repeat behavior, or what happens if the key is already down.

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?

It is a single compact sentence with the core action front-loaded and no wasted words. The release guidance is placed immediately after the action, which is appropriate.

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 one-parameter input tool with no output schema, the description covers the essential action and release lifecycle. It could be more complete by clarifying focus or repeated-call behavior, but little critical context is missing.

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 would need to compensate for undocumented parameters, but it says nothing about the key parameter. The enum makes valid values obvious, but the description adds no meaning about modifiers, aliases, or how the key argument interacts with holding.

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 states a specific verb and resource: hold a key down. It also distinguishes the tool from its release-oriented siblings by naming key_up and key_release.

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?

It explicitly tells the agent how to release the held key, naming key_up for a single key and key_release for all keys. It gives clear lifecycle guidance but does not contrast key_down with key_tap or explain when holding is preferred over tapping.

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