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 mentions the action (creates) and allowed types, but fails to disclose any side effects, required permissions, or outcomes (e.g., what the response contains). For a mutation tool, this is a significant gap.

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 a single concise sentence that front-loads the action and includes useful type examples. It is appropriately sized with no wasted words. Slightly more structure (e.g., listing required fields) would improve it, but it is efficient.

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 tool with 5 parameters, 2 required, and no output schema, the description is minimal. It does not explain the relationship between entity_type and custom fields, nor does it mention that required fields (name and client_slug) exist. However, the schema provides detailed parameter descriptions, so the agent can infer some context. The description is adequate for basic use but lacks depth.

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 80% (per signal), and most parameters have descriptions. The description adds limited value beyond the schema—listing example types that overlap with the schema's own type description. It does not clarify the meaning or constraints of parameters like group_id or client_slug beyond what the schema provides. Baseline 3 applies because schema covers most of the parameter semantics.

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 tool creates a new custom field for an entity, with specific verb+resource. It provides example types (text, numeric, checkbox, select, date) and distinguishes from siblings like get_custom_fields or update_custom_field. Aims is unambiguous.

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 gives no guidance on when to use this tool versus alternatives. There is no mention of prerequisites, differences from other custom field operations, or scenarios where this tool is appropriate. It merely describes the action without context.

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