list_roster

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

No annotations are provided, so the description bears full responsibility. It declares no side effects, explains that empty strings for road/model are normal, and clarifies that the tool lists all locomotives. Slightly lacking in potential performance/scalability notes, but adequate for a read-only 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 front-loaded with the core purpose, followed by usage context, edge case handling, and explicit exclusion. Every sentence adds unique value without redundancy, making it well-structured and concise for modern LLM context windows.

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 zero parameters and no output schema, the description fully informs what the tool returns (name, DCC address, road, model) and handles edge cases (empty strings). It also explains the tool's role in the broader workflow with sibling tools, making the context complete.

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?

There are no parameters (0 parameters, 100% schema coverage). Baseline for 0 params is 4. The description adds value by explaining the contents of the list, which goes beyond the schema.

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 'every locomotive in JMRI's roster', listing the fields returned. It distinguishes itself from the sibling tool 'find_locomotive' by noting that this tool provides a full list while the sibling resolves a name to an address.

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?

Explicitly states when to use this tool (before acquire_throttle/set_speed, which require DCC addresses) and when not to (automatic name-to-address resolution, for which it directs to find_locomotive). Provides concrete usage context.

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