key_up

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

With no annotations, the description takes on the full burden of disclosure. It reveals the raw event nature, the inverse behavior, the accepted key formats, and the special RELEASE_ALL effect, which is valuable behavioral context. It doesn't discuss session_id, but that's a shared parameter rather than a tool-specific behavior.

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 only three sentences, with the first stating the core purpose, the second clarifying the inverse relationship, and the third detailing the special case. Every sentence adds value, and it is efficiently front-loaded.

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 simplicity (two parameters, output schema present), the description covers purpose, relationship, and a special value. However, it omits any explanation of session_id and leaves key formats implicit, which could be more explicit. Overall it's sufficient but not exhaustive.

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 coverage is 0%, so the description must compensate for missing parameter information. It partially does for 'key' by referencing key_down's formats and the special RELEASE_ALL value, but it leaves 'session_id' entirely unexplained and does not enumerate key format options. The compensation is incomplete.

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 tool's function: 'Inject a raw BBC keyup event into the matrix.' It also differentiates itself from key_down by directly stating it's the inverse, making its purpose unambiguous.

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?

Provides explicit guidance by positioning itself as the inverse of key_down and documenting the RELEASE_ALL special case for clearing all held keys. It doesn't explicitly list exclusions, but the relationship to key_down is clear enough for an agent to know when to use this tool.

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