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

Annotations already declare readOnly, idempotent, non-destructive, openWorld, so the safety profile is covered. The description adds meaningful behavioral context by naming the exact fields returned and the 'known trails' scope, which is what makes the empty-result fallback necessary.

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 short sentences: purpose and return fields first, then the downstream id usage, then the fallback. No filler and the most decision-relevant information leads.

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 exists, yet the description compensates by naming the returned fields (name, length, bounds, exposure coverage) and explaining what to do when a trail is missing. Complete for a zero-parameter discovery tool.

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 tool takes zero parameters, which is the baseline-4 case. The description still adds value by establishing the id/trail_id naming contract consumed by downstream tools, linking this call's output to other tools' inputs.

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 and resource ('Lists the trails WTDS knows by name') and immediately enumerates the returned attributes (length, bounds, exposure data). This distinguishes it from the sibling search/fetch tools that return arbitrary web results.

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?

Explicitly routes the agent onward: use a trail's id as trail_id in get_trail_weather or route_weather, and if a trail is absent, send the route itself. Both the when-to-use and the fallback are named, leaving nothing to inference.

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