Bulk create custom fields

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

Annotations already declare write/idempotency/open-world traits, and the description adds non-trivial behavioral context: it mutates account configuration and OAuth is mandatory (API keys rejected). It still does not disclose bulk atomicity (partial-failure behavior) or that a confirm flag gates the operation.

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 short, front-loaded sentences with no filler; the mutating nature and auth requirement land first. Efficient, though slightly terse given the tool's breadth.

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?

No output schema exists and the tool is a complex nested bulk mutation, so the description should do more. It omits partial-failure semantics, the payload vs payload_file mutual exclusion, and when confirmation is required, leaving those entirely to the schema.

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 67% and the parameters are largely self-documented, including the nested payload/custom_fields structure and the confirm flag. The description adds no parameter meaning at all, 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 ('Bulk create custom fields'), and the 'bulk' qualifier implicitly distinguishes it from the single-record create_custom_field sibling. It is clear without opening the schema, though it never explicitly names the sibling it differs from.

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?

Gives a prerequisite (OAuth required, API keys unsupported) but no explicit when-to-use / when-not guidance versus create_custom_field or bulk_update_subscriber_custom_field_values. The auth constraint is context rather than routing guidance.

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