List QGIS Instances

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

Beyond the readOnlyHint annotation, the description discloses the tool's output details (reachability, which QGIS answered) and the default instance selection logic. This gives the agent useful behavioral expectations for a read-only discovery tool without contradicting the annotation.

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: the first lists the output fields and the second gives practical usage guidance. No filler, every sentence serves a purpose, and the most important information 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?

For a simple, read-only, no-parameter tool with an output schema, the description covers everything needed: what it does, what it returns, why to use it, and how it ties into the rest of the API. It is fully complete for the agent to select and invoke correctly.

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 has zero parameters, so the schema is complete and the description naturally adds no parameter-specific details. The baseline of 4 for 0 parameters applies here; the description still provides useful context about the 'instance' parameter used elsewhere, but not for this tool's own parameters.

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 configured QGIS instances with specific fields (name, host, port, reachability, version, PID, window title, profile). The verb 'List' combined with the resource 'configured QGIS instances' is specific and distinguishes it from the many sibling tools focused on layers, layouts, or project settings.

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?

It explicitly instructs use 'before writing to it' to confirm which window a name maps to. It also explains how the instance parameter behaves across other tools, including the fallback to 'default' or the first listed instance, giving clear when-to-use and how-to-use context.

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