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

Annotations already declare readOnly/idempotent/openWorld, so the description is free to add real value: it warns that missing coordinates or conditions 'remain unknown' (partial results are possible), which is non-obvious and prevents false conclusions. The scope caveat about not being live navigation guidance adds further context. It doesn't state how complete a typical result is or whether misses return an error versus an empty result.

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: purpose first, then return contents, then caveats. No filler or redundancy. Slightly list-like in the middle sentence, but every clause carries information.

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 an output schema present, the description needn't spell out return structure, and it still previews the return categories usefully. For a read-only, three-param lookup, the main remaining gap is telling the agent that slug/routeId likely come from search_peaks/search_routes beforehand.

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 67%, with slug and query documented but routeId left bare. The description adds no parameter-level guidance — it doesn't clarify that query is a free-text name match or how slug, routeId and query interact (e.g., whether all three must agree). Baseline 3 for mid coverage with no compensating detail.

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: 'look up a named waypoint or difficult passage on a route', and enumerates what comes back. Clearly narrower in scope than a whole-route tool like get_route, though it never names that sibling to sharpen the contrast.

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 by 'named waypoint or difficult passage' and the exclusion 'this is not live navigation guidance' sets a domain boundary. However, no tool-level alternative is named (e.g., use get_route for the full route overview, search_routes to find a routeId first), so the agent must infer when this is the wrong call.

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