da_list_displays

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. The description clearly implies a non-destructive read operation by listing metadata (id, bounds, scale, rotation, primary). It doesn't state whether it requires system permissions or how it handles multiple displays, but the read-only nature is reasonably clear from context. Since it's a listing operation with no schema hints, this is adequate if not rich.

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 clean, single sentence that lists the exact data fields returned. Zero waste, no fluff, and front-loaded with the verb and resource. Every word earns its place.

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?

This is a simple, zero-parameter, no-output-schema listing tool. The description enumerating the return fields (id, bounds, scale, rotation, primary flag) is sufficient for a tool of this complexity. While there's no output schema to provide structure, the description covers the essential return value shape adequately. Could mention return format details but for a simple listing tool this is complete enough.

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?

With 0 parameters, there's nothing for the description to explain about parameter semantics. The schema is empty and needs no compensation. The description does describe the return fields, which serves as useful semantic context for what the agent will get back. A baseline 4 is appropriate since no parameter documentation is needed.

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 uses specific language ('List connected displays') with a clear verb and resource, and enumerates the exact data fields returned (id, bounds, scale factor, rotation, primary flag). It clearly distinguishes from siblings like da_move_mouse and da_get_mouse_position since it deals with displays rather than mouse actions.

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?

The description implies this is a discovery/listing tool used to gather display metadata, which would precede operations like moving the mouse (da_move_mouse) or taking screenshots (da_screenshot). However, it doesn't explicitly state when to use it vs alternatives or mention any prerequisites. The application context is reasonable but implied rather than explicit.

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