key

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

Annotations (readOnlyHint=false, destructiveHint=false) correctly signal a non-read, non-destructive action, and the description adds real behavioral context beyond them: the IME interception of character keys and the game-walking use of hold. It stops short of explaining which window receives the keystroke (focus dependency) or what the call returns, but the essential behavior is disclosed.

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?

Front-loaded with the action and examples, then parameter meanings, then the sibling redirect — three tight sentences with no wasted wording. Every clause carries information an agent needs.

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 input-simulation tool with no output schema, the description covers purpose, all parameters, and the alternative tool, which is nearly everything needed. The one gap relative to the sibling set is not mentioning the `focus` dependency, i.e., that the target window must be focused first.

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 carry all parameter meaning, and it does: `keys` is a key or combination with examples, `hold` is seconds held down, `times` is repeat count. Units and intent are clear for all three; only edge cases (e.g., valid key names) are left implied.

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?

States a specific verb and resource — press a key or key combination — with concrete examples ("ctrl+s", "esc", "w") and Mac variant. It explicitly distinguishes itself from the sibling `type` for text entry, so an agent can tell the two apart without opening either schema.

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?

Gives explicit routing: character keys go through the input method, so use `type` for entering text. It also clarifies the purpose of `hold` (walking in games) and `times` (repeat count), telling the agent when those options apply rather than leaving it to guesswork.

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