create_custom_field

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does not mention mutational aspects, potential side effects (e.g., effect on existing contacts), uniqueness constraints, reversibility, or permissions. The only behavioral detail is the list of supported types, which is insufficient for a create 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?

The description is appropriately sized: two sentences and an example. It is front-loaded with the core purpose, then details supported types, and ends with a practical example. Every sentence adds value, and there is no redundant wording.

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 tool's simplicity (3 parameters, no output schema, no nested objects), the description is largely complete. It defines the operation, lists supported types, and offers a clarifying example. It does not mention what the tool returns or any limitations (e.g., duplicate labels), but these are not critical for a basic create tool.

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?

The schema already describes all three parameters (label, options, field_type) with 100% coverage, so the baseline is 3. The description adds value through the example, which clarifies how options apply to dropdown fields and demonstrates realistic usage. This lifts the score to 4.

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 clearly states the action ('Create a new custom field') and the target resource ('for contacts'). It also lists the supported field types and provides a concrete example, effectively distinguishing it from sibling tools like create_contact or list_contact_fields.

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 description implies when to use the tool (when a new custom field for contacts is needed) and provides a usage example. It does not explicitly state when not to use it, but the supported types serve as an implicit exclusion. Since there are no direct sibling alternatives, clarity is adequate.

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