directions

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

With no annotations, the description must fully disclose behavior. It notes ETAs are in ISO-8601 in the destination's local timezone. But it does not mention side effects, data permanence, authorization needs, or rate limits. Some behavioral context is provided, but gaps remain.

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 three sentences and about 60 words, efficiently conveying purpose, a usage hint, and output format. It is front-loaded with the main action. Minor redundancy could be trimmed.

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 no output schema, the description partially compensates by explaining output format (ISO-8601 ETA). Parameter details are missing due to schema mismatch. Compared to siblings, this is the only directions tool, so differentiation is less critical. Still, more detail on inputs and edge cases would improve completeness.

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?

The input schema is an empty object (no parameters), yet the description references 'preset', 'costing', and 'truck_*' knobs. This contradiction reduces trust. The description adds meaning beyond the schema, but the schema's emptiness makes the added info suspect. Baseline from high schema coverage does not apply because schema is nonexistent.

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 it generates routes, ETAs, and turn-by-turn directions. It uses a specific verb ('Generate') and resource ('routes, ETAs, and turn-by-turn directions'). Among siblings like geocode, explore, and traffic, this is distinct as the only routing tool.

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 advises preferring the 'preset' arg over raw costing, with examples like car_default, truck_53, etc., and explains that presets keep trucks on freight corridors. It mentions advanced callers can use raw knobs. However, it does not explicitly state when not to use this tool or list alternatives for similar tasks.

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