zen_press_key

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

No annotations are provided, so the description carries full burden. It discloses that the tool uses BiDi input.performActions and supports key combinations, but does not mention potential side effects, error behavior, or whether the action is instantaneous or waits for completion. Adequate for a straightforward keyboard input tool.

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?

The description is concise with two sentences. The first sentence states the core action and method, and the second adds capabilities. No redundant or unnecessary words, and critical information is 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?

Given the tool's simplicity (2 parameters, no output schema, no nested objects, 1 required), the description is fully adequate. It covers purpose, usage hints (BiDi), and an alternative sibling. No additional context needed.

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% and both parameters (key, modifiers) have detailed descriptions in the schema. The description adds that it supports special keys and combinations but does not provide new meaning beyond the schema. Baseline score of 3 is appropriate.

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 description clearly states the tool sends keyboard input to the active page using BiDi input.performActions, and lists supported special keys and modifiers. It distinguishes from sibling zen_fill by noting that zen_fill is for text input, providing a clear verb-resource-action definition.

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 description explicitly directs users to use zen_fill for text input, providing a clear alternative and context for when to use this tool vs. a sibling. However, it does not discuss prerequisites or scenarios when not to use the tool beyond text input.

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