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

No annotations are provided, so the description carries the burden. It discloses the key targeting logic ('Targets an element when a selector is given, otherwise the focused one') and clarifies it is not a device-level press. It doesn't cover error conditions or waiting behavior, but the core behavior is well explained.

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, each with a distinct purpose: the action and examples, the targeting behavior, and the device scoping. No redundancy, and the core constraints are front-loaded.

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 three-parameter tool with no output schema, the description covers the action, allowed keys, target selection, and alternative routing. Minor details like return values or error handling are absent but don't impede correct invocation.

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 baseline is 3. The description adds slight enrichment by explaining targeting behavior and giving example keys, but it doesn't significantly go beyond the schema descriptions for pageId, key, and selector.

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 ('Press a key'), resource (DESKTOP grid browser by pageId), and lists valid key examples. It also explicitly differentiates from device-level presses and routes phone/tablet usage to webpage_press_key.

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 provides an alternative and a when-not: 'Not a device — for a phone or tablet use webpage_press_key.' It also scopes usage to the desktop grid browser context, so an agent knows exactly when to select this tool.

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