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

Annotations already declare readOnlyHint=true and destructiveHint=false, which the description does not contradict. The description adds useful behavioral context beyond annotations: it restricts results to 'public, approved' entities and provides an explicit usage instruction to 'Cite canonicalUrl and preserve original source links.'

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 a single dense sentence that front-loads the core action ('Get one public, approved highway or canal') before listing the included data. The list of returned fields is long but purposeful, and the separate instruction about canonicalUrl is direct and actionable.

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?

For a one-parameter, read-only retrieval tool with an output schema, the description provides sufficient context: what is returned, access restrictions, and how to handle source links. It does not describe error behavior for invalid IDs, but that is minor given the simple contract and read-only annotations.

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 input schema fully documents the only parameter (`id`) as 'Persistent numeric Atlas highway ID,' so schema description coverage is 100%. The description adds no additional parameter-level meaning, so the baseline score of 3 is appropriate.

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 clearly states a specific verb ('Get'), a specific resource ('one public, approved highway or canal'), and enumerates the included data (geometry, metadata, groups, evidence, attachments, links). This distinguishes it from sibling search tools like search_highways and find_highways_near_location, which are used for discovery rather than retrieval by ID.

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 clearly implies the tool is for fetching a single known entity by ID, given the required `id` parameter and the focus on full detail. It does not explicitly name alternatives or state when not to use it, but the context is strong enough for an agent to select it appropriately.

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