Cheapest train per day

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

Beyond the annotations' safe, read-only profile, the description clarifies that prices are in Toman per adult and that a missing day means no train operates. It does not discuss price freshness or availability, but the added output semantics are useful and prevent misinterpretation.

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 compact and front-loaded with the tool's purpose, followed by workflow guidance and two important result-interpretation details. Every sentence earns its place without repeating schema-level constraints.

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?

For a simple four-parameter lookup with complete schema descriptions and clear safety annotations, this supplies the information needed to select and invoke it correctly. It also covers the conceptual result shape, units, and empty-day meaning despite the absence of an output schema.

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 100%, including date formats, day ranges, and accepted city identifiers. The description's reference to a start date reinforces the schema but adds little parameter guidance beyond it, so the high-coverage baseline of 3 applies.

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 gives a specific verb, resource, and scope: listing the lowest train price for each day from a start date. It also distinguishes the tool from al_trains by positioning it as the flexible-date, cheapest-day selection step.

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?

It explicitly says to use this tool before al_trains when the travel date is flexible. This provides both a clear usage condition and the appropriate sibling tool for the subsequent search.

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