list_custom_fields

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

Annotations already declare readOnlyHint=true, so the safety profile is covered and the bar is lower. The description adds that contact and opportunity fields are served by different internal endpoints, which is extra context, but it says nothing about pagination, result size, or ordering for a list 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?

Two front-loaded sentences with no filler; the purpose comes first and the parameter constraint second. The closing note about internal API endpoints is mildly tangential but short enough to earn 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?

For a one-parameter read-only list tool with no output schema, the description covers location scoping and the entity-type requirement adequately. Additional detail on return shape or pagination would help but is not critical given the annotations.

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 coverage is 100% and the single parameter's enum and description are fully documented in the schema, so the schema does the heavy lifting. The description restates that model selects the entity type (contact or opportunity) without adding format or behavioral detail beyond the schema.

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 gives a specific verb (List) and resource (custom fields) scoped to the current GoHighLevel location, and names the two entity types it operates over. It is clear on its face, but does not explicitly differentiate itself from nearby siblings like list_custom_values or list_business_fields, so it stops short of a 5.

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?

It states that a model parameter must be supplied and what that parameter selects, which implies the usage context (listing fields for contacts vs opportunities). There is no explicit when-to-use/when-not-to-use guidance and no routing to an alternative sibling for related data such as custom values.

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