search_stations

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

With no annotations provided, the description carries the full burden and does well by disclosing key behaviors: it describes the return format (dictionary with stations list and count), default and max values for limit, and search constraints (minimum 2 characters for query). It doesn't cover rate limits or authentication needs, but provides substantial operational context.

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 well-structured and front-loaded with the core purpose, followed by detailed parameter explanations and examples. Every sentence adds value—no redundancy or fluff—making it efficient and easy to parse for an AI agent.

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 moderate complexity (3 parameters, no annotations), the description is complete: it explains purpose, usage, parameters, return values, and provides examples. With an output schema present, it doesn't need to detail return structure further, and it adequately covers all necessary context for effective tool 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?

Schema description coverage is 0%, so the description must compensate fully. It adds significant meaning beyond the schema: explains that 'query' searches station names with a 2-character minimum and can be empty to list all, clarifies 'country_codes' format and provides examples, and specifies 'limit' default and max values. This covers all parameters thoroughly.

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 specific verb ('search') and resource ('train stations') with filtering capabilities ('by name or filter by country'). It distinguishes from siblings like 'get_departures' (focused on departure times) and 'search_trips' (focused on trip planning) by emphasizing station code retrieval for trip planning.

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 explicitly states 'Use this tool to find station codes needed for trip planning,' providing clear context for when to use it. However, it doesn't mention when NOT to use it or explicitly compare to sibling tools like 'search_trips,' which might be a better alternative for certain trip-related queries.

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