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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so safety is covered. The description adds genuine non-obvious behavior: results are ranked by data completeness rather than raw length, specifically so service roads and sidewalks are deprioritized, and it discloses what fields come back. It omits result-count limits or pagination.

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, front-loaded with the core action before the ranking rationale and the usage trigger. The clause about service roads and sidewalks is slightly ornamental but does concretely justify the ranking choice, so it mostly earns its place.

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 names the return fields (distance, elevation gain, route shape). Annotations carry the safety profile and the schema fully documents all three parameters. Minor gaps remain around result volume/pagination and what happens when no trails are known in the radius.

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%, with latitude/longitude ranges and the radius default (25) and max (100) all documented in the schema. The description adds no syntax or format detail beyond the schema's own wording, so the baseline of 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 and resource ('Find named hiking trails') plus the scope ('within a radius of a coordinate') and the ranking rule. The resource is unmistakably distinct from the sibling tools check_conditions and find_campgrounds, so an agent can route on the description alone.

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?

Provides an explicit trigger: 'Call this when someone asks what to hike near a place.' That is clear positive guidance. It stops short of a 5 because it names no alternatives or exclusions (e.g., pointing to find_campgrounds for overnight sites or check_conditions for weather).

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