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

Annotations already declare the safe read-only, open-world profile, so the bar is lower. The description adds real value beyond that by enumerating returned fields (stop count, driver, distributed/started/completed state) and the 20-per-page cap, which compensates for the absent output schema.

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?

A single tightly-packed sentence that front-loads the action and resource, then adds definitional and pagination detail with no waste. The endpoint reference is a compact addition rather than 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?

With no output schema, the description usefully lists the fields returned and the page-size cap. It is largely complete for a paginated list tool, though it omits ordering/sort behavior and any filtering context beyond the date parameter.

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 description coverage is 100%, so page_token, max_page_size, and starts_on_or_after are already fully documented in the schema. The description's 'up to 20 per page' merely restates the schema's max_page_size maximum, adding no new parameter meaning; baseline 3 applies.

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?

States a specific verb ('List') and resource ('routes') and goes further by defining what a route is ('one driver's run of a plan: stop count, driver, distributed/started/completed state'). This definition lets an agent distinguish routes from plans and stops, which matters given the many list_* siblings.

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 only implied by the resource name; there is no explicit when-to-use or when-not-to-use guidance. It never points to alternatives such as get_route for a single route or list_route_stops for the stops within a route, which is a notable gap in a dense sibling set.

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