accessibility

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

Annotations declare destructiveHint=true but not which actions are destructive; the description fills that gap by naming the mutating actions ('invoke, set_value, toggle and select change the app') and explaining that destructive target names require user confirmation. It also documents aliases, the coordinate space of returned elements, and pagination via '+N more'/offset.

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-loads the highest-value guidance ('START HERE', the preferred-over-computer rule) before the long action list. It is dense and long, but for a 24-action tool nearly every sentence carries routing or safety information, so the length is largely justified.

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?

With no output schema, the description does the required work of describing return shapes ('one line per element — [Role] "name" @x,y w×h ... plus value=') and pagination. A few actions (state, list_children, wait_for, smart_read/smart_type) get no explanation, but the core read/act path is fully covered.

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 100%, so the schema already documents every parameter and a 3 is the baseline. The description adds real value beyond it: alias mapping (click/set-value/get-value), the fact that read_tree/find use SCREEN coordinates clickable via `computer click` space:"screen", and the element_id+snapshot_id handoff flow.

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?

Opens with a specific verb+resource ('see and drive a window: the OS accessibility tree') and enumerates the concrete capabilities (read names, find by name/role, invoke, toggle, expand/collapse, set value, select, query state). It cleanly distinguishes itself from sibling `computer` by describing a name-based accessibility approach versus coordinate clicking.

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?

Explicitly states precedence: 'Always preferred over computer.click(x,y) when the target has a name', with the reasons (DPI, resize, layout shifts). It also routes to alternatives for hard cases: use compile_ui / find_button / find_field for 'sparse/ambiguous UIs'.

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