Create a custom field.

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

Annotations already declare readOnlyHint=false, destructiveHint=true, idempotentHint=false, and openWorldHint=true, so the safety profile is covered. The description adds nothing beyond that: it does not explain that the mutation requires confirm=true, does not mention the payload vs payload_file exclusivity rule, and does not describe side effects of creating a field. With annotations present the bar is lower, but zero added context keeps this at a 2.

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?

It is a single short sentence, so there is no bloat, but this is under-specification rather than conciseness. The one sentence carries no useful information an agent could not get from the tool name alone.

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 non-idempotent, destructive mutation with five parameters including a nested payload object and mutually exclusive payload/payload_file options, the description omits everything an agent needs: the confirm requirement, the body-vs-file exclusivity rule, and the meaning of the account parameter. Annotations cover safety and the schema covers parameters, but the definition as a whole gives no operational context.

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 five parameters (label, account, confirm, payload, payload_file) are already documented in the schema. The description adds no additional parameter meaning, which lands at the baseline 3 for high schema coverage.

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?

Tautological: description restates name/title.

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 guidance on when to use this tool versus alternatives. With siblings such as list_custom_fields, list_all_custom_fields, and create_segment nearby, an agent gets no signal about prerequisites, ordering, or when creating a field is the right move. No when/when-not/alternative information is present.

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