open_app

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

No annotations are provided, so the description must disclose behavioral traits. It mentions opening an app and returning a success/failure message, but omits details like whether already-open apps are brought to front, required permissions, or error handling for missing apps.

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 concisely structured with a clear purpose, usage guideline, args, and returns section. Every sentence adds value with no redundancy or fluff.

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 simplicity of the tool (one parameter, no nested objects) and the presence of an output schema (implied), the description adequately covers the essentials. It lacks details on error conditions but is sufficient for a basic open-app tool.

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?

The schema provides a 'name' parameter with no description (0% coverage). The description adds value by giving examples: 'Mail', 'Contacts', 'Messages', clarifying the expected format beyond the bare 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?

The description clearly states the tool's purpose: 'Open any mac application by specifying its name.' This verb+resource combination is specific and distinct from sibling tools like hide_app or quit_app.

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 provides a specific scenario: 'Use this tool if you encounter any error or issue mentioning that the app is not open.' This gives clear context for when to use it, though it doesn't list alternatives or exclusions for other common cases.

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