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

With no annotations, the description carries the transparency burden. It usefully discloses that the actual download happens externally on cityheart.run after a one-time €7.99 Stripe payment and that CityHeart never charges through chat, which prevents the agent from implying an in-chat purchase.

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 carrying distinct value: main purpose, payment/behavioral caveat, and usage context. It is front-loaded and contains no filler.

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?

For a low-complexity, single-parameter tool without an output schema, the description covers the URL purpose, external payment behavior, and appropriate trigger point. It does not detail error cases or private-route handling, but those are minor given the simple contract.

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% and the single parameter slug is already well documented with an example. The description adds little parameter-specific meaning beyond the schema, matching the baseline for high schema coverage.

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 states a specific action and resource: returning a GPX download/checkout URL for a public route. It clearly differentiates this from route-finding and generation siblings by positioning it as the final export/checkout step.

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 explicitly says to use it after the user has picked a final route via find/get_details and confirmed intent. It provides a clear sequencing condition, though it does not list alternatives to exclude.

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