transit_systems

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

Annotations already declare readOnlyHint=true, and the description's 'List' aligns with this. The description adds the specific count (12) and the included fields (regions, capabilities), providing useful context beyond the annotation. No safety concerns or side effects need disclosure for a simple list operation.

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, well-structured sentence that immediately conveys the tool's purpose and output. Every word earns its place, with no redundancy or extraneous detail.

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 list tool with readOnlyHint annotation, the description is complete. It specifies the exact set of systems, the included attributes, and implicitly signals that no other inputs are needed. There is no output schema to document, and the description covers the return value sufficiently.

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 description compensates by clearly explaining what the response contains (all 12 transit systems with regions and capabilities). Since there is no schema to document parameters, the description fully carries the semantic burden and does so effectively.

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 verb 'List' and the resource 'all 12 available US transit systems', specifying the output includes regions and capabilities. This distinguishes it from sibling tools like bart_stations or septa_train_view, which operate on specific systems, making it a unique catalog tool.

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 implies this tool is used to discover available transit systems, but it does not explicitly compare it to alternatives or state when not to use it. Given many transit siblings exist, more explicit guidance would be helpful, but the context of listing systems is clear.

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