Create custom field

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

The description adds a valuable non-recoverable behavior: the data type cannot change after creation, which is not encoded in annotations or schema. Since annotations already signal that this is a mutating, non-idempotent operation, the extra permanence warning is strong added context.

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?

The description is two short sentences with no filler; the core action comes first and the critical design constraint follows immediately. Every sentence earns its place.

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?

Given the annotations and a schema that lists required parameters and extra_data examples, the description is nearly sufficient. It covers the one non-obvious constraint (type immutability), though it omits details such as return value and duplicate-name behavior, which are not critical for correct invocation.

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?

With 67% schema coverage, the schema already explains data_type and extra_data, including select/monetary requirements. The description adds meaningful semantics for data_type (immutability), but it does not explain the 'name' parameter or add details that the schema lacks for the remaining fields.

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 uses a specific verb-resource pairing ('Define a new custom field') and the word 'new' clearly distinguishes this creation action from sibling update_custom_field, get_custom_field, and delete_custom_field. There is no ambiguity about what the tool does.

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 timing is implied by 'new' and the permanence warning suggests using this tool only when a custom field with a deliberate type is needed. However, it does not explicitly name alternatives like update_custom_field or say when not to use it, so the guidance is only implicit.

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