browser_os_type

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

With no annotations provided, the description must carry the burden of behavioral disclosure. It does so by stating it uses 'REAL OS keystrokes' (bypasses DOM events), targets the currently focused element (not a selector), requires macOS and Accessibility permission, and only works when in-page typing fails. This is substantial transparency. It doesn't mention error handling or blocking behavior, but the critical constraints are disclosed.

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 concise sentences with no fluff. The first sentence states the core function and its distinguishing feature (REAL OS keystrokes). The second sentence gives the when-to-use, prerequisite, and platform requirement. All essential information is front-loaded and every clause earns its place.

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?

The description covers the purpose, usage condition, prerequisite, and platform constraint. However, it omits any explanation of the 'modifiers' parameter, which is a required part of the input schema (though not required, it's optional). For a tool that types OS-level keystrokes, modifiers are a common need (e.g., typing Ctrl+A). The lack of this information means an agent might call the tool with incorrect or missing modifier syntax. Additionally, it doesn't specify what happens on failure (e.g., if permission is denied), but that's minor compared to the parameter gap.

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 explain both parameters. While 'text' is implicitly described as the content to type, the 'modifiers' parameter is completely ignored. An agent has no idea what values to pass (e.g., 'ctrl', 'shift') or how they affect the keystrokes. This is a significant gap for a tool whose schema provides no descriptions.

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 states a specific verb and resource: 'Type text using REAL OS keystrokes into whatever currently has focus.' It clearly distinguishes itself from in-page typing (likely browser_type) by emphasizing OS-level keystrokes and the isTrusted condition. This leaves no ambiguity about what the tool does.

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 states when to use: 'Use only when in-page typing fails because the element checks event.isTrusted.' It also gives a prerequisite ('Focus the field first') and a platform constraint ('macOS only'). This is clear guidance that prevents misuse and routes the agent away from normal typing tools.

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