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

readOnlyHint=true already declares the safety profile, so the description only needs to add context. It contributes the source endpoint (GET /assets/custom_attributes.api) and the shape of the returned data ('names and ids'), which is useful given there is no output schema. It says nothing about whether fields are per-asset-type, scoped by business, or paginated.

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?

Two short, front-loaded sentences with no filler. The trailing API-path sentence earns its place only as a behavioral hint, which keeps it just short of a 5.

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 zero-parameter read-only lookup, the description supplies what the annotations and empty schema cannot: what the returned records contain. Without an output schema, however, it could have said more about the return structure (e.g. whether ids are usable as field keys elsewhere).

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 tool takes zero parameters, so the schema imposes no documentation burden and the baseline of 4 applies. The description correctly implies no input is required.

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 resource: the custom fields defined for items, and narrows the payload to names and ids. An agent can tell it apart from the other list_* siblings (locations, groups, coupons) because no sibling touches custom attributes. It stops short of a clear verb, but 'List custom fields' in the title plus the description makes the operation unambiguous.

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?

No when-to-use guidance and no alternative tool is named. The parenthetical '(names and ids)' hints that this is a lookup to obtain field identifiers, but the description never says so, nor does it mention any prerequisite or follow-up tool.

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