vm_sendkey

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 well: it discloses the pre-agent timing window, the one-combo-per-call constraint, and the recommended screenshot verification loop. It does not, however, mention error behavior (e.g., what happens if keys are unrecognized or the display is not focused), leaving some gaps for a mutation-style input tool.

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?

Three short sentences, front-loaded with the accepted key vocabulary followed by the workflow constraint and the verification tip. No sentence is filler.

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?

An output schema exists, so return values need not be explained, and the description covers purpose, timing, and invocation cadence. The main omission is the meaning of 'name' and 'hold_ms', which leaves the call specification slightly incomplete.

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 compensate. It does partially: the enumerated key names ('ret', 'esc', 'ctrl-alt-delete', 'shift-f10', etc.) effectively document the accepted values for 'keys'. But 'name' (presumably the VM identifier) and 'hold_ms' (default 100) are never explained, leaving two of three parameters undocumented.

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 (send) and resource (a key combo to the VM display), and explicitly differentiates itself from the closest sibling by noting it drives text-mode installers 'BEFORE the guest agent exists (the part vm_exec cannot reach).' An agent can select between vm_sendkey and vm_exec 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 when-to-use (pre-guest-agent text-mode installers), names the alternative it is not (vm_exec), and prescribes the operating rhythm: 'One combo per call; screenshot after each to see the installer's reaction.' Nothing is left to inference.

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