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

With no annotations, the description carries the behavioral burden. It discloses that the tool computes the cheapest option through one transfer city and includes prices for both legs. However, it does not describe output format, pagination, or behavior when no transfer route is available.

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 a single tight sentence that front-loads the usage condition and clearly states the result. Every word contributes value, with no repetition of the title or schema.

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 absence of an output schema, the description does well by specifying the result type: cheapest option via one transfer city with prices for both legs. It could be more complete by indicating what happens when no transfer route exists, but it is sufficient for a simple two-parameter search tool.

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%: both parameters are described identically in the schema as city names or slugs. The tool description adds no parameter-specific meaning beyond that, so the baseline score 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 clearly states the tool finds the cheapest route via one transfer city with prices for both legs, specifically for cases when no direct bus exists. This distinguishes it from direct-route and destination-ranking siblings like search_routes and cheapest_destinations.

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 opening phrase 'Когда прямого автобуса нет' gives a clear condition for when this tool is appropriate. It does not name alternatives explicitly, but the context makes the intended usage obvious relative to direct-route tools.

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