list_controllers

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

With no annotations provided, the description carries the full burden for behavioral disclosure. It includes '(L0 read-only)', which signals a safe, non-mutating operation, adding some transparency. However, it does not describe any other behavioral traits such as return format, error conditions, or environment requirements. For a simple listing tool, this is adequate but not rich.

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 sentence that front-loads the action ('List') and resource ('ros_control controllers and their states'), with a helpful read-only caveat. Every word earns its place, and there is no unnecessary verbosity. It is ideally sized for the tool's simplicity.

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?

Given the tool has no parameters and an output schema is present, the description does not need to explain return values. It covers the core function and a safety qualifier, but it lacks any usage context (e.g., when to use versus alternatives) or mention of environment prerequisites. For a simple list tool, this is mostly complete, with minor gaps.

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, and the input schema is empty, indicating 100% schema coverage. Since there are no parameters to explain, the description does not need to add parameter semantics. The baseline of 4 is appropriate, as the schema fully covers inputs.

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 ros_control controllers and their states, using a specific verb ('List') and a specific resource ('ros_control controllers'). While it does not explicitly differentiate from sibling tools, the resource is distinct enough to avoid confusion with list_topics or list_nodes, and the 'L0 read-only' qualifier adds scope clarity.

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 no guidance on when to use this tool versus alternatives. It does not mention exclusions, prerequisites, or alternative tools, leaving the agent to infer usage purely from the tool's name and description. This is a clear gap for a tool that has sibling listing operations like list_topics and list_nodes.

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