isochrone

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

No annotations are provided, so the description carries the behavioral disclosure burden. It does this well by specifying the polygon ring as [lon, lat] pairs, area_m2 units, decimal-degree coordinates, and the 1–120 minute budget range. It does not discuss side effects, but this is a spatial query tool and the core behavior is clearly disclosed.

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 compact and well structured: a one-sentence purpose, a unit/format legend, and a fully worked example. Every sentence earns its place and the most important information appears first.

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?

With an output schema present and a fully documented input schema, the description provides the essential operational facts: coordinate order, units, time-budget bounds, and an example call. It is sufficient for invoking the tool correctly, though it leaves usage-vs-alternative routing to inference.

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 already documents all four parameters with 100% coverage, so the baseline is 3. The description adds a meaningful example and confirms units, but it largely restates schema-level details (decimal degrees, minutes 1–120) without adding deeper parameter-specific trade-offs or nuances.

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 opening phrase 'Reachable-area polygon within a travel-time budget' is a specific, concrete summary that clearly states the tool's output and resource type. It is conceptually distinct from the geo sister tools, though it does not explicitly name siblings or describe exclusions.

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 implies usage: use this tool when you need a reachable-area polygon for a given travel-time budget. The example reinforces the intended call shape, but there is no explicit guidance about when to prefer this over geocode, pois, bbox_summary, or reverse_geocode.

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