travel_time

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

With no annotations provided, the description carries the behavioral burden. It discloses traffic-aware delay vs baseline, transit leg details, extra computation for tolls, and API restrictions (arrival_time only for transit). It does not mention auth, rate limits, or error handling, but for a routing API this is substantial transparency.

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 organized with clear line breaks separating the core purpose from parameter details. Every sentence adds value, using concrete examples (e.g., RFC3339 format) without excessive verbosity. It front-loads the purpose and then details each parameter efficiently.

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 has 7 parameters and an output schema exists, the description covers the essential usage context, parameter semantics for most parameters, and special behavioral traits (traffic, transit legs, toll computation). The missing avoid_tolls is minor, and overall the description is complete enough for an agent to invoke the tool correctly.

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. It explains origin/destination formats, mode values and defaults, RFC3339 time formats, the departure/arrival semantics, and include_tolls behavior. However, it omits the avoid_tolls parameter entirely, leaving that one parameter undocumented despite the schema having no description either.

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 computes route duration and distance between two points, with specific behavioral modes (traffic-aware driving, step-by-step transit). It positions itself as 'THE tool for when do I need to leave?', distinguishing itself from sibling tools like geocode or place_search which handle locations, not routing.

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?

Provides clear context on when to use it (routing, ETAs) and mode-specific constraints (e.g., arrival_time is transit-only). It does not explicitly name alternatives or state when not to use it, but the context is strong enough for an agent to select it appropriately.

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