plan_trip

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

With no annotations provided, the description carries a heavier burden, and it does well by disclosing important behavioral nuances: backends differ by region, and fares_min/fares_max must not be misinterpreted as interchange discounts. It doesn't cover every possible output or error behavior, but the key caveat is prominently surfaced.

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 tight and well-structured: the core action first, followed by regional routing scope, then a critical warning. Each sentence adds distinct value and there is no filler or repetition.

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 moderate-complexity tool, the description covers the most important context: router selection and a non-obvious fare/discount caveat. A minor gap is that there is no explicit return-shape description despite no output schema, but the warning about response fields partly mitigates this.

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%, so the baseline is 3. The description adds no additional input-parameter meaning; the fares_min/fares_max warning relates to response semantics rather than the schema parameters themselves.

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's core function with a specific verb and resource: 'Plan a transit trip.' It adds concrete distinction by naming the routing backends for different regions, which separates it from sibling tools like search_location and hello_tool without ambiguity.

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 clear context that this tool is for trip planning and explains regional routing behavior: Wheels Router for Hong Kong and Transitous for other regions. It does not explicitly name sibling alternatives or when-not-to-use conditions, but the action and routing scope make the intended usage apparent.

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