List open application windows with handle, title, process, position and foreground status, optionally grouped by app, to inspect running UI before acting.
List open windows: hwnd, title, process (the real application for UWP), position, foreground. by_app=true: grouped by application. Example: {"by_app": false}
| Name | Required | Description | Default |
|---|---|---|---|
| by_app | No | ||
| visible_only | No |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint and non-destructive, so safety is covered and the description is not required to restate it. The description does add genuine value by enumerating the returned fields and clarifying that "process" is the real owning application for UWP apps — a non-obvious detail. It says nothing about ordering, snapshotting, or how many windows to expect.
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?
It is short and front-loaded with the purpose and return fields, which is good. But the 'Example: {"by_app": false}' line is a wasted, ambiguous fragment that contradicts the by_app=true sentence above it.
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, listing the returned fields is necessary and partially done, but the visible_only parameter and the difference from the sibling "window" tool remain unexplained. For a simple two-parameter read tool this is passable but leaves real gaps an agent would hit on first call.
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 description coverage is 0%, so the description must compensate. It explains by_app (grouped by application) but never mentions visible_only, which defaults to true and materially changes the result set. Half the parameters are effectively undocumented.
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 opening clause gives a specific verb plus resource ("List open windows") and even enumerates the returned fields (hwnd, title, process, position, foreground), so the agent knows exactly what it gets. It does not, however, distinguish itself from the sibling tool named "window", which sounds adjacent enough to require a disambiguation sentence.
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 only usage signal is the by_app toggle behavior; there is no statement of when to use this versus siblings like "window" or "look", and no exclusions or preconditions. The trailing example {"by_app": false} is also at odds with the preceding by_app=true explanation, adding confusion rather than guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.