list_routes

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

With no annotations, the description carries the full burden. It discloses important behavior: mode values are enumerated, omitting mode returns all modes, and limit controls max results. It does not mention potential ordering or edge cases, but the listed behaviors add meaningful context beyond the bare schema.

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 concise and well-structured: a one-sentence purpose followed by a compact Args section. Every sentence adds value, and the format is easy to scan.

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's simplicity (2 optional parameters), the description fully covers invocation details. An output schema exists, so return values are pre-defined. The mode and limit parameters are completely documented, and the purpose is clear. No critical gaps for selection or invocation.

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 input schema has 0% description coverage, so the description must compensate. It does so thoroughly by enumerating all valid mode values, explaining that omitting mode lists all modes, and defining limit as the maximum number of results. This adds significant meaning beyond the schema's bare property names.

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 uses a specific verb ('List') and resource ('public transport routes'), with a clear optional mode filter. It distinguishes itself from sibling tools like search_stops and get_next_departures by focusing on routes rather than stops or departures.

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 usage by stating what the tool does, but it does not explicitly mention when to use this tool over alternatives (e.g., search_stops, get_next_departures, run_sql_query). No exclusions or when-not-to-use guidance is provided.

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