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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real behavioral context beyond that: traffic is excluded (so results are static estimates), travel is one-way and not round-trip, and out-of-coverage places are refused with the region named rather than returning a fallback. That refusal behavior is decision-relevant and not derivable from the schema.

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?

Four short sentences, front-loaded with what is returned and its units before input format and caveats. No filler, padding, or redundancy; each sentence carries a distinct fact.

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?

There is no output schema, so the description must convey return values, and it does: minutes and km, one-way. Input shape, traffic caveat, and coverage-failure behavior are all stated. A minor gap is the absence of any resolution or latency expectations for address geocoding failures, but for a simple two-parameter read this is close to complete.

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%, with both 'from' and 'to' documented as address-or-coordinates and identical to the description's phrasing. The description adds no syntax, format, or defaulting detail beyond the schema, so the baseline 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 states a specific verb+resource with units: road drive time (minutes) and distance (km), one-way, between two places. This is far more precise than a name restatement. It does not, however, name or contrast with routing siblings such as plan_day_routes, technician_route, or nearest_technicians, so sibling differentiation is left implicit.

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?

There is no when-to-use guidance, no prerequisites, and no alternative tools named. An agent must infer from the name alone that this is the single-pair routing primitive while plan_day_routes handles multi-stop optimization. Nothing in the text routes the agent between these options.

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