open_app

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

With no annotations, the description carries the full burden. It discloses the key behavior: it brings the app to front and launches it if not running. It does not mention error handling or return values, but for a simple activation tool this is sufficient and not misleading.

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 a single, front-loaded sentence that states the core behavior first, then a usage hint. There is zero wasted text and the example is included without padding.

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 tool with one parameter, no output schema, and no annotations, the description is nearly complete. It explains the action, the launch-if-needed behavior, and the parameter format. Minor omissions (e.g., behavior when the app is already frontmost) are easily inferred and do not hinder 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?

The schema already documents the 'name' parameter at 100% coverage, so baseline is 3. The description adds value by specifying the exact format (as shown in Finder) and gives a concrete counter-example ('Google Chrome', not 'chrome'), which improves the agent's ability to supply a correct value.

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 action (bring to front, launch if not running) and a specific resource (application), with an explicit example distinguishing it from similar tools like open_url or file_open. It clearly tells an agent 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 gives a precise parameter-usage hint (use Finder name, e.g., 'Google Chrome' not 'chrome') but does not explicitly say when to prefer this tool over alternatives like get_frontmost_app or manage_windows. The context is clear but no exclusions or alternative-selection guidance is provided.

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