system_set_window_frame

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

Annotations already cover the write/idempotent/open-world profile, and the description adds context beyond them: the Accessibility API dependency, the required 'accessibility' permission, and the fact that only the frontmost focused window is affected. It still says nothing about failure behavior when no window is focused, multi-monitor coordinate handling, or the human-approval flow implied by _approvalId.

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?

Two short sentences with the action front-loaded, followed by a bracketed metadata tag. No filler, but the metadata tag is cryptic and the description is arguably too terse given the parameter ambiguity.

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?

An output schema exists so return values need not be explained, and annotations cover the safety profile. However, for a 6-parameter mutation with an approval/idempotency workflow, the description omits the approval requirement and any coordinate semantics, leaving gaps an agent must guess at.

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 only 33%: x, y, width and height carry empty descriptions, and the tool description adds nothing about the coordinate space (origin, monitor-relative vs global, negative values allowed down to -20000). For a geometry-setting tool, the meaning of these four required parameters is the single most important thing to explain, and it is absent from both description and schema.

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 pair (move/resize) plus a precisely scoped resource (the frontmost focused window) and the mechanism (Accessibility). It is implicitly distinct from read-only siblings like system_get_active_window and system_list_windows, but it never names them, so differentiation is left to inference.

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 routing signal is a negative capability statement ('Does not implement arbitrary UI clicking'), which excludes a use case that no sibling offers anyway. There is no guidance on when to pick this over system_get_active_window, system_activate_app, or system_open_app, and no stated prerequisites for success.

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