List running applications

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

Annotations already declare readOnlyHint and idempotentHint, so the safe read-only nature is covered. The description adds value by disclosing the specific output fields (pid, bundle identifier, window count, frontmost), which are not part of the annotations. This gives the agent a clear expectation of the tool's behavior beyond what structured data provides.

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, well-structured sentence that front-loads the action ('List running applications') and lists the key output fields without unnecessary verbosity. Every word adds value, making it highly concise and easy to parse.

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 simple read-only listing tool with good annotations and full schema coverage, the description is largely complete. It specifies the output fields but does not mention any default ordering, sort behavior, or whether the list is filtered by default. Given the low complexity, this is a minor gap, so a score of 4 reflects that it is almost complete.

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 input schema has 100% coverage for the single optional parameter, with a clear description of the query parameter's filtering behavior. The tool description does not add any additional parameter context, so the baseline score of 3 is appropriate given the schema already fully documents the parameter.

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 lists running applications, which is a specific verb and resource. It distinguishes itself from siblings like hs_list_windows by specifying the output fields (pid, bundle identifier, window count, frontmost). This makes the purpose unambiguous and differentiates from other list/focus tools.

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 implies usage by listing what the tool returns, but it does not explicitly state when to use this tool versus alternatives such as hs_list_windows or hs_focus_app. There are no exclusions or alternative suggestions, leaving the usage context implicit rather than explicit.

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