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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so safety and side-effect expectations are fully covered without the description. The description adds only output units and coordinate-order emphasis, saying nothing about routing-engine behavior, latency, or the 5x5 cap beyond what the schema enforces.

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, front-loaded with the core resource and units, with no wasted phrasing. The indented 'Note:' formatting is slightly awkward but the content is worth keeping because coordinate ordering is a common failure point.

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, so return-value explanation is unnecessary, and annotations cover the safety profile. For a 3-parameter, 100%-documented schema the description supplies enough to invoke correctly, though it omits any note on the small batch limits or the network data source.

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 100%, so the schema already documents origins, destinations, and the mode enum. The description's note about [latitude, longitude] ordering restates the schema's own '[[lat, lon], ...]' descriptions, adding reinforcement but no new meaning; the units of the result are output semantics covered by the output schema.

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 uses a specific verb-resource pairing ('Network travel time ... and distance ... from each origin to each destination') and states units (minutes, metres), so an agent can tell it computes a routing-based matrix rather than a single route or straight-line distance. It does not name the sibling tools it differs from, so it falls short of a 5.

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?

Usage is implied by the phrase 'network travel time', which signals routing-network results as opposed to the geometric measure a tool like calculate_distance would give. There is no explicit when-to-use, when-not-to-use, or named alternative among route, isochrone, or calculate_distance, so the guidance is inferred rather than stated.

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