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

Annotations already declare read-only, idempotent, open-world, non-destructive behavior, so the safety profile is covered. The description adds real context beyond that — results are network-based travel times rather than straight-line estimates, and the output units are minutes and metres. It omits whether results are symmetric, how missing/unreachable pairs are reported, or that mode changes the network used.

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?

Two sentences, zero filler, with the delivered values front-loaded and the coordinate-format caveat placed where it is needed. Nothing here repeats the title verbatim or wastes words.

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?

An output schema exists and annotations cover the safety profile, so the description needn't explain return shape. But for a routing tool with three parameters and a strong sibling set, the absence of any mention of mode (default walk) and of any disambiguation from route/calculate_distance leaves meaningful gaps.

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 67%, with origins/destinations documented as [[lat, lon], ...]; the description reinforces the latitude-first ordering, which is the highest-risk mistake for this tool. The mode parameter, which materially changes the answer (walk/bike/drive), is never mentioned in the description and has no schema description beyond its enum and default.

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?

States a specific computation (network travel time in minutes and distance in metres) across each origin-to-destination pair, which is concrete enough that an agent knows exactly what it gets back. It does not, however, distinguish itself from close siblings like route or calculate_distance, so the agent must infer that this is the many-to-many variant.

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 at all: nothing says to pick this over calculate_distance (straight-line) or route (single itinerary), and no input constraints (e.g. why one would batch up to 5x5 points) are explained. The only usage-adjacent content is a coordinate-order note, which is parameter formatting, not routing guidance.

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