List custom field definitions and filter them by contact, deal, or company entity type to identify available fields for data mapping.
List custom field definitions. Filter by entity type (contact, deal, or company) to see available fields.
| Name | Required | Description | Default |
|---|---|---|---|
| page | No | Page number (default 1) | |
| per_page | No | Results per page | |
| entityType | No | Filter by entity type |
Changes observed during successful MCP inspections.
v4.71.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full disclosure burden. "List" implies a read operation, but the description does not state read-only guarantees, permission requirements, pagination defaults (page/per_page exist in schema but behavior is unstated), or result ordering.
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 short sentences, front-loaded with purpose followed by the primary filtering hint. No filler or redundancy, though the second sentence is somewhat sparse for what it needs to convey.
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 simple 3-parameter list tool with full schema coverage, the description is adequate but thin. It does not describe the return shape (no output schema exists), pagination behavior, or permission prerequisites, leaving gaps an agent may need to infer.
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 the schema already documents all three parameters including the entityType enum. The description restates the entity-type filter but adds no syntax, default, or behavioral detail beyond what the schema provides.
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?
States a specific verb+resource ("List custom field definitions") that an agent can immediately distinguish from create/update/delete_custom_field siblings. It does not explicitly name siblings, but the name and first sentence make the read-only retrieval intent 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 second sentence implies usage: filter by entity type to see available fields for contact/deal/company. However, there is no explicit when-to-use vs. when-not-to-use guidance, no mention of pagination behavior for large result sets, and no routing to sibling tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.