apps_interface_input

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

Annotations already declare destructiveHint=true, idempotentHint=false and openWorldHint=true, and the description adds genuinely new behavior: delivery only confirms 'sent/dispatched events' rather than actual effect, and guide_start 'does not approve access or I/O'. It does not spell out what state a mis-aimed click could destroy, but the dispatch-vs-effect caveat is the key risk note for this 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?

Five compact sentences, action list front-loaded, then prerequisites, exclusions, and verification in descending priority. No filler or restatement of the title.

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 destructive, non-idempotent input injector with no output schema, it covers prerequisites, permission boundaries, delivery semantics, and how to verify results. The remaining gap is the meaning of instanceId/generation (staleness guards for a mutation), which an agent must infer.

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 50%, and the description fills the most important gap by defining pointer coordinates as normalized App coordinates and scroll deltas as CSS pixels, which the schema does not say. The event type list is echoed from the nested event schema, and instanceId/generation remain undefined in both places.

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 opens with a concrete verb set (click, drag, scroll, type, key/chord) scoped to 'the active device App interface', which is specific enough to select it against apps_host_input and apps_operation_status. It stops short of naming apps_preview_input as the alternative for preview-only flows, so sibling differentiation is only partly explicit.

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 gives explicit routing ('Use apps_host_input for Menu/Device'), a prerequisite ('Read apps_input_targets first'), an exclusion ('Permission dialogs remain human-operated'), and a verification path ('use screenshots/App state to verify'). That is when-to-use, when-not, and alternatives all in one paragraph.

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