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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is covered structurally. The description adds genuinely non-obvious context the annotations cannot: the required custom_fields:write scope. However, it says nothing about downstream effects, such as whether existing custom field values become orphaned or are cascaded away when the definition is removed.

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 with zero padding; the operation and the identifier are front-loaded before the permissions note.

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?

The scope requirement and identifier are present, and annotations cover the destructive/idempotent profile. Still missing is the consequence of deletion for dependent custom field values, which is the main thing an agent should know before invoking a destructive, non-reversible-content call.

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?

Only one parameter, and schema description coverage is 100% with a UUID format and regex pattern already documented. The description's 'by ID' restates what the schema conveys, so the baseline of 3 is appropriate.

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 and resource ('Delete a custom field definition') plus the identifier used, so an agent can distinguish it from create_custom_field_definition, update_custom_field_definition and delete_custom_field_value by name alone. It stops short of noting the distinction from the sibling delete_custom_field_value, which matters in this catalogue.

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?

There is no guidance on when to use this tool versus update_custom_field_definition or delete_custom_field_value, and no prerequisites or warnings are given before an irreversible removal. The description is purely declarative.

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