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

With no annotations provided, the description carries the full burden and discloses key behavioral facts: it returns matching locations with coordinates, covers marinas/moorings/water points/other waterside facilities, and is limited to waterway locations. It does not mention edge cases like no results or result limits, but for a simple lookup it provides sufficient transparency.

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?

The description is three sentences, with the primary purpose first, practical usage second, and a scope-limiting caveat third. Every sentence adds value and there is no repetition or 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?

This is a simple one-parameter lookup tool with no output schema, so the description's mention of returning coordinates and facility types provides reasonable expectations. It also situates the tool within the larger workflow by referencing plan_route and plan_round_trip, making it complete for its low complexity.

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 schema already fully describes the single 'name' parameter with examples, and schema description coverage is 100%, so the description adds limited extra semantics. The description reinforces that the name is a place or facility name on the waterways, which is useful but not a major addition beyond the schema.

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 uses a specific verb ('Look up') and a clear resource ('place name on the British inland waterway network'), and it states the return value ('matching locations with coordinates'). It also distinguishes itself from siblings by explicitly noting it is not a general geocoder, differentiating it from tools like search_directory.

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?

The description gives concrete use cases: disambiguating a place before plan_route or plan_round_trip, and getting coordinates for a known spot. It also states a clear when-not ('not a general geocoder'), though it does not name an alternative tool for general geocoding, so it stops short of full alternative guidance.

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