qt_list_instances

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

No annotations are provided, so the description must carry the full behavioral burden. It discloses the key qualifier that only probe-instrumented apps appear (not every Qt process) and enumerates what is shown, but says nothing about read-only safety, whether it's a snapshot at call time, or what happens with zero results.

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 tight sentences with the core definition front-loaded and the follow-up guidance second. Every clause contributes; nothing is 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?

An output schema exists, so the description needn't re-explain return values, and there are no parameters to document. For a simple discovery tool this is close to complete, with only the safety profile and empty-result behavior left unstated.

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 tool takes zero parameters, which is the baseline-4 case; there is nothing to disambiguate. The description correctly implies the tool is argument-free and that the id comes out of the result rather than going in.

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 and resource: 'List running Qt apps that have the qtpy-mcp probe', with example targets (Houdini, Blender, Maya). It's clearly a discovery/listing tool, though it doesn't explicitly distinguish itself from the sibling qt_list_windows, which an agent could easily confuse it with.

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?

Gives actionable downstream guidance: use the returned id 'with the `instance` argument of any tool, or with qt_select_instance'. That establishes the role as the entry point to all other tools. It stops short of saying when NOT to use it (e.g. vs qt_list_windows) or what an empty result means.

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