Search train routes

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint. Description adds accent-insensitivity, 'every word must match' constraint, sorting by renown with route-name matches first, and the fallback to listing whole atlas without query. No contradictions.

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?

Packs essential information into one coherent paragraph without fluff. Front-loaded with main action. Could be slightly more structured (e.g., bullet points), but current form is efficient and clear.

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?

Covers all necessary aspects: what it does, how to use, parameter behaviors, sorting, fallback, and links to related tools. Despite no output schema, describes return format (compact per-route facts with id and URL). Fully sufficient for competent use.

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?

Schema coverage is 100% with good descriptions. The description adds context about query matching fields and omission behavior (browse all). Does not detail limit maximum (schema handles it), but adds value beyond schema. Baseline 3, plus 1 for extra context.

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?

Description clearly states 'Free-text search over every route in the TrainRouter atlas' and lists matched fields (name, cities, train, operator, countries). Distinct verbs and resource, with explicit differentiation from siblings like get_route, famous_routes, city_pair.

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 tells when to use this tool vs alternatives: 'Use get_route with a returned id for full detail, famous_routes for a ready-made top list, city_pair for A-to-B journey times.' Also explains behavior with no query.

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