Custom Fields Get By Entity Id

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

Annotations already declare readOnly/idempotent/non-destructive, so the description's job is the extra context it does provide: required OAuth scopes broken out per entity family and the API version (2025-03). It does not mention rate limits or response/pagination behavior, but the auth requirement is a real addition beyond annotations.

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 purpose, then the HTTP route, then scope requirements and API version as separate lines. Four lines with no filler; the scope line is dense but each element is 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 read-only 4-parameter lookup with full schema coverage and complete annotations, the description supplies exactly the missing operational context: route, per-entity scopes, and API version. No output schema exists, but a keyed lookup's result shape is implied by the purpose statement.

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% and every parameter (entity enum, entity_id, fields, response_format) is already documented in the schema. The description adds no syntax or format detail beyond echoing example entity values, so the baseline of 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: 'Get the custom field values of one entity instance', with a concrete example (one product). Combined with the endpoint path it clearly separates this from definition-oriented siblings, though it never names those siblings explicitly.

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 per-entity scope list implies which entity types are readable and under what permissions, but there is no explicit 'use this when…' guidance or a named alternative such as custom_fields_list or custom_field_defs_get. The agent must infer the choice from the name and the endpoint line.

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