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

With no annotations, the description carries the full burden and does a solid job: it discloses return contents (ordered stops, what to know, coordinates, on-foot distance, total time), a meaningful exclusion (tram/metro/ferry legs removed and flagged separately), and a coverage limitation. Auth, rate limits and error behavior are unstated, keeping it short of a 5.

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 tight sentences, front-loaded with the payload description before the exclusions and coverage caveat. The unnamed 'nine cities' line is slightly unactionable but still earns its place as an expectation-setter.

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?

No output schema and no annotations, so the description must describe the return, and it does: ordered stops, per-stop detail, distance and total time, plus the multimodal-leg exclusion. Adequate for a read-only content tool, though the shape/format of the response is only described prose-wise.

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%, so both parameters (city, hours enum 3/6/12) are already fully documented in the schema. The description adds only tangential context ('total time') and does not clarify the hours semantics beyond what the enum already conveys, so the 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?

The description states a specific verb+resource: a curated stop-by-stop walking route for a city, and enumerates what each stop carries (notes, coordinates, distance, time). The purpose is unambiguous, but it never explicitly names or contrasts with the siblings (compare_destinations, destination_costs, find_destinations), so differentiation is left to inference.

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 implied (fetch a walk for a city) and there is a partial when-not: nine cities deliberately have no route. However, it neither names those cities nor points to an alternative tool for those cases, so the guidance is incomplete.

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