isochrone

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

With no annotations provided, the description fully discloses the return format ('GeoJSON FeatureCollection with one Polygon per contour') and explains how to use the output with mapping libraries. It also notes constraints like max values and mutual exclusivity, ensuring transparent behavior.

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 well-structured with sections (purpose, output, contours, use cases) and uses bold for emphasis. Every sentence is informative without redundancy, achieving conciseness and clarity.

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 the tool's complexity (mutual exclusivity, multiple parameter types, GeoJSON output), the description covers all necessary information: purpose, parameter rules, output format, and integration examples. No output schema exists, but the description compensates adequately.

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?

Although input schema coverage is 100%, the description adds significant value by reinforcing mutual exclusivity, providing example values, stating the default mode ('auto'), and explaining the output format. This goes beyond the schema's bare definitions.

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 'Generate a reachability polygon' and specifies the geographic area reachable from a point within a given time or distance. It distinguishes itself from sibling tools by mentioning specific use cases like delivery zone visualization and service area planning.

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 provides explicit guidance on when to use the tool (e.g., 'show restaurants within 15 min walk') and includes clear instructions for the contours parameters: 'you must provide EITHER contours_minutes OR contours_meters, not both and not neither', with examples and constraints.

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