delete_custom_fieldRemove a custom field definition by ID from SendGrid to clean up contact data and prevent unused fields from cluttering records.
Delete a custom field definition
| Name | Required | Description | Default |
|---|---|---|---|
| field_id | Yes | ID of the custom field to delete |
Changes observed during successful MCP inspections.
v1.1.1Input schema / additionalPropertiesRemoved value: -falsev1.0.0Input schema / $schemaAdded value: +"http://json-schema.org/draft-07/schema#"Input schema / additionalPropertiesAdded value: +falseDoes the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description does not contradict the annotations, but it also adds no behavioral context beyond them. For a destructive operation, it omits useful details such as whether deletion is permanent or whether it affects contacts/data that use the custom field. The idempotent and destructive hints carry the disclosure burden alone.
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, front-loaded sentence with no filler or repetition. Every word contributes to identifying the operation and the target resource.
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 delete tool, the core invocation details are present: action, resource, and required field_id. However, the description omits the consequences of deletion and any guidance on how to find the field_id, so it is not fully complete for an agent operating without prior context.
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%: field_id is documented as 'ID of the custom field to delete'. The description adds no further nuance, but none is required because the single parameter is fully explained by 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 uses a specific verb ('Delete') and names a precise resource ('custom field definition'), which clearly distinguishes it from sibling tools like create_custom_field, update_custom_field, and list_custom_fields. It is immediately obvious what action an agent would take with this tool.
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 provides no guidance on when to choose this tool instead of create_custom_field or update_custom_field, nor does it mention prerequisites such as how to obtain the field_id (e.g., via list_custom_fields). An agent must infer usage solely from the tool name and inline schema.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.