search_trains

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

With no annotations, the description carries full burden. It discloses default behavior for missing departure_datetime (searches from current time), pagination default of 10 results per page, and the need to request different pages. It also explains flexible date formats, offering rich behavioral 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 as a docstring with a one-line summary followed by per-parameter explanations. Each entry is concise yet informative, with no wasted words.

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?

The description covers all four parameters, explains default behaviors, and provides usage context. Since an output schema exists, return values need not be described. This is complete for a tool of this complexity.

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 explain each parameter. It does so thoroughly: origin and destination include examples, departure_datetime lists multiple accepted formats and default behavior, and page explains the default and result count. This adds substantial meaning beyond the bare 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 opens with 'Search for train journeys between two stations with pagination,' clearly identifying the action (search), resource (train journeys), and key behavior (pagination). This distinguishes it from sibling tools like find_station and get_train_prices.

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 provides a clear context for when to use the tool—searching train journeys between two stations—but does not explicitly state when-not-to-use it or mention alternative tools. This matches 'clear context, no exclusions'.

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