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

Annotations already cover read-only/idempotent safety, but the description adds non-obvious behavior: an empty list is the normal answer, curated routes skip the adjacency check by construction, and zone-adjacency providers will refuse custom routes unless the trail graph has been crawled. That is context an agent cannot derive from structured fields.

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?

Front-loaded with the core purpose before routing guidance and edge cases, and each sentence carries distinct information. It is longer than most list-tool descriptions and slightly overstuffed, but no sentence is 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?

An output schema exists, so return values needn't be explained, and the description still tells the agent how to consume the returned id and how to interpret an empty result. For a read tool with sibling alternatives, nothing an agent needs to call it correctly is missing.

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% for both park_id and pets_only, so the schema carries parameter meaning and the baseline of 3 applies. The description mentions a 'variant's id' only as an output value, adding nothing beyond what the schema already documents for the input parameters.

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: pre-planned multi-night traverses for a park, grouped by trail with pace variants. The 'Rockwall, 4 nights' vs 'Rockwall, 3 nights' example makes the unit of return unambiguous and distinguishes it from siblings like get_zone_map or list_park_campgrounds.

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 says 'START HERE for any multi-night trip,' names the downstream tool (create_itinerary) and the parameter to feed (route_id), and explains what to do when a custom route is refused. When-to-use and what-to-do-instead are both stated, not inferred.

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