tool_open_application

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

With no annotations, the description carries the full burden, and it discloses important behavioral traits: it is labeled MUTATING (soft), serialized across agent sessions, and may take focus. This goes beyond a bare 'open' statement. The term 'soft' is somewhat informal, but the sentence adds genuinely useful side-effect context.

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 compact sentences with no filler: the first establishes the operation and examples, the second adds critical behavioral caveats. Every clause earns its place, and the key purpose 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?

The tool is simple (one required parameter) and has an output schema, so the description does not need to explain return values. It covers what is opened, how, and the relevant side effects (session serialization, focus stealing), making the definition complete for an agent deciding whether and how to call it.

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 0%, so the description must compensate for the single 'target' parameter. It does so by defining target as a file, folder, or URI and giving examples (.exe path, document, URL). It could add path-format or URI-scheme details, but the required meaning is clear enough for correct invocation.

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?

States a specific verb ('Open') and a precise resource class ('a file, folder, or URI') via the shell's default handler, with concrete examples like .exe paths, documents, and URLs. This clearly distinguishes it from the UI-automation siblings, none of which launch external default-handler targets.

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 clear mental model — same as double-clicking in Explorer — so an agent knows to use it when it wants OS-level default handling rather than window/element manipulation. It does not explicitly name alternatives or exclusion conditions, but the sibling tools are sufficiently distinct that no close alternative needs to be ruled out.

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