route_isochrone

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

No annotations are provided, so the description carries the full burden. It discloses external service dependency, that it adds a layer (EPSG:4326), and that only a summary is returned. However, it lacks details on error handling, rate limits, or whether the operation is destructive. The disclosure is adequate but not exhaustive.

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?

Three sentences, each adding value: purpose, key parameters and limits, and dependency/result. No fluff, front-loaded with the action.

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 moderate complexity and the presence of an output schema, the description covers the main aspects: what it does, key parameters, external service, and result (adds layer, returns summary). It does not mention error scenarios or prerequisites, but it is sufficient for selection and basic invocation.

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 has 0% description coverage, so the description must compensate. It explains minutes (list, default [15], cap 4), costing (examples), and base_url (custom instance). It does not explain lat, lon, or layer_name, but lat/lon are self-explanatory. Overall, it adds meaningful semantics beyond the 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 clearly states 'Compute isochrones (reachable-area contours) from a point using Valhalla.' This is a specific verb-resource pair and distinguishes it from sibling routing tools like route_valhalla or route_osrm.

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?

It explains the context: capped at 4 contours, uses a community-run demo (best-effort, no SLA), and allows custom instances. It does not explicitly exclude alternatives or provide when-not-to-use, but the context is clear enough for an agent.

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