Screen and monitor information

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

With readOnlyHint=true already covering safety, the description still adds real behavioral context: a measured platform limitation (Services.appShell.screenManager undefined in Firefox) meaning only the current screen is ever returned and other monitors cannot be enumerated or named. That prevents an agent from assuming multi-monitor discovery is possible; the absence of return-shape detail keeps it from a 5.

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 sentences, front-loaded with what is reported, then the hard limitation, then the workaround. Every sentence carries distinct information an agent would otherwise have to discover by trial and error.

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?

No output schema exists, but the description names the returned fields (size, usable area, window position within it) and explains the multi-monitor failure mode plus the alternative path. Only the exact return structure and units are left unstated.

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?

Zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. No parameter-relevant claims are made or 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?

States a specific verb and resource: reports the size, usable area and window position of the screen the window is on. It also carves out its boundary against browser_set_window_position, so an agent can separate the read side from the write side without opening a 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?

Explicitly routes multi-monitor placement to browser_set_window_position and notes coordinates can be negative, which is clear alternative-tool guidance. It does not say when to prefer this over the related sibling browser_get_window_geometry, leaving that one comparison to inference.

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