Get custom field

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

Annotations already declare readOnly, idempotent, non-destructive, and openWorld behavior, so the safety profile is covered. The description adds genuinely useful context beyond that: it identifies the required OAuth scope (custom_fields:read) and notes it reads account data, which an agent needs to authorize the call correctly.

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?

Three terse fragments with the operation name front-loaded and no padding. 'Get custom field' is somewhat redundant with the title, but the auth-scope sentence is dense and useful, and nothing is wasted.

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 simple read getter with full schema coverage and no output schema, the definition is minimally adequate. It covers auth and the read-only nature, but says nothing about the shape of the returned custom field object, forcing the agent to call it blind.

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 all three parameters (account, publication_id, custom_field_id) are already documented in the schema, including the account-defaulting behavior. The description adds no parameter detail, so the 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?

The description 'Get custom field' essentially restates the name and title without elaboration. It does convey a verb+resource (retrieve a single custom field), and the sibling set (create/list/update/patch/delete_custom_field) makes the retrieval intent inferable, but the description itself does nothing to distinguish this from list_custom_fields or to describe what a custom field is.

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?

There is no when-to-use or when-not-to-use guidance. It never mentions that list_custom_fields should be used to enumerate fields versus this tool for a single one, nor any prerequisite for obtaining a custom_field_id. The agent must infer the usage pattern entirely from the name.

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