Custom Fields List Owners

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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower. The description adds genuinely useful behavior context: the per-entity OAuth scope required (read_products for categories/products/products-variants, read_customers, read_orders) and the pinned API version 2025-03, which tells the agent an authorization failure is likely if the wrong scope is missing.

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?

Four short, front-loaded lines: purpose first, then route, then scope, then response envelope. Nothing is repeated from the schema, though the raw HTTP path is somewhat incidental for an agent that already has the tool bound.

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 six parameters, no output schema and no nested objects, the description does the needed work by disclosing the return envelope {count, page, per_page, has_more, next_page, items[]} and the scope prerequisites. It stops short of saying what an 'owner' item actually contains, but the pagination and auth picture is complete enough to call it correctly.

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%, so the schema already documents entity, custom_field_id, page, per_page, fields and response_format. The description adds only the entity-to-scope mapping, not format, allowed values or interpretation of the ID types, so baseline 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 -- list the entity instances that hold a value for a given custom field -- and backs it with the concrete HTTP route GET /{entity}/custom-fields/{custom_field_id}/owners. It is distinguishable from custom_fields_list (lists the field definitions) and custom_fields_set_values, though the description never explicitly contrasts them.

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?

Usage is only implied: an agent can infer it should call this when it needs to know which products/customers/orders actually carry a value for a field. There is no explicit when-to-use or when-not, and no sibling alternatives are named (e.g. custom_fields_get_by_entity_id for the reverse lookup).

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