Resize or move the browser window

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

The description discloses that this is a mutating BiDi window-state command and clarifies the coordinate space is window pixels, which is real context beyond readOnlyHint=false. However, it does not explain what happens to omitted coordinates (does x alone move without resizing?), whether the operation is clamped by screen bounds, or what the call returns.

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: what it does, what to read first, and how it differs from the viewport tool. Nothing is repeated from the schema and the unit caveat is front-loaded where it matters.

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 five-optional-parameter mutation with no output schema, the description covers routing, prerequisite reads, and units, which is most of what an agent needs. The remaining gap is default/partial-argument behavior, partly covered by the clientWindow schema note about the active window.

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 baseline is 3, but the description earns a bump by disambiguating units: window pixels versus page pixels, which the schema does not state. It also frames the four geometry fields as position and size, mapping cleanly onto x/y/width/height.

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 ("Set the client window position and size") and names the underlying BiDi command, so the effect is unambiguous. It differentiates itself from browser_set_viewport but not from the closer siblings browser_set_window_state and browser_set_window_position, which an agent could easily confuse with this one.

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 an explicit prerequisite ("Read the current geometry with browser_list_windows first") and an explicit exclusion with the alternative named ("use browser_set_viewport when you mean the page viewport instead"). It stops short of disambiguating against browser_set_window_state / browser_set_window_position, the most likely wrong picks.

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