key_up

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

No annotations are provided, so the description carries the full disclosure burden, yet it says nothing about behavior beyond the verb: what happens if the key is not currently held, whether the call is idempotent, whether it fires autofocus/hover side effects, or whether modifier state changes. For an input-injection tool with zero annotation coverage this is a real gap.

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?

One short, front-loaded sentence with no filler. It is efficient, though the brevity comes at the cost of the missing semantics noted elsewhere rather than being tight-but-complete.

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?

The tool is mechanically simple, but with no annotations, no output schema, and an indistinguishable sibling (key_release), the description should at minimum cover the key_down pairing and the release-vs-tap distinction. It leaves all of that out.

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 should compensate, but it adds nothing about the single `key` parameter. It does not say the value must match the key previously passed to key_down, nor that aliases ('comma' vs ',') are interchangeable — the enum constrains values but not this semantic contract.

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?

"Release a held key" states a specific verb and resource, which is better than a tautology. However, the sibling list contains both key_release and key_down, and the description gives no clue how key_up differs from key_release — an agent cannot disambiguate from the text alone.

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?

There is no statement of when to use this versus key_release or key_tap, and no mention of the obvious pairing with key_down (press then release). The pairing must be inferred entirely from the tool name.

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