list_services

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

With no annotations provided, the description carries full burden. It declares no arguments and specifies the return format (an object with a services array). While it doesn't explicitly state read-only behavior, listing services is inherently non-destructive. The example return value adds transparency.

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?

Three sentences, each essential: what it does, what it takes, and how to use it. No wasted words, front-loaded with the main purpose. Ideal conciseness.

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 parameterless tool with an output schema, the description covers purpose, usage, and return structure completely. The example service name and the hint to use before call_service provide full context for the agent to decide and invoke.

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 schema has no parameters (100% coverage by default). The description confirms 'Takes no arguments,' which adds no extra meaning but meets the baseline for zero-parameter tools.

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 'List all ROS services currently available on the robot,' specifying both the verb (List) and the resource (ROS services). It effectively distinguishes from sibling tools like list_topics and list_nodes by naming the specific resource type.

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?

Provides explicit usage guidance: 'Use before call_service to find the exact service name.' This tells the agent when to invoke this tool and hints at a workflow sequence, making the purpose and timing unambiguous.

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