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

Goes well beyond the destructiveHint annotation: discloses the mandatory two-step preview/confirm flow, that stored values are NOT deleted but become unread orphans that reappear if the key is redefined, that built-in fields can't be removed, and that an unknown key returns the object's custom field keys. This is exactly the non-obvious behavior an agent needs.

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?

Front-loads the action and the DESTRUCTIVE warning, then details consequences — good ordering. The "When to use" paragraph largely restates the first paragraph (preview then confirm, orphans returning), so a small amount of text is redundant.

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 destructive mutation with an output schema already covering the return value, the description supplies the destructive semantics, the two-step safety flow, the permission boundary, and the orphan-value behavior. Nothing an agent needs to call it safely is missing.

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 schema already documents key (not label), object_type, and the confirm preview semantics. The description reinforces the confirm flow but adds no syntax or format detail beyond what the schema provides, so baseline 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 — "Remove a custom field's DEFINITION by object_type + key" — with the scope qualifier that only the definition (not values) is removed. This clearly distinguishes it from siblings like define_field, update_field, and archive_object.

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?

Provides an explicit "When to use" (an admin retiring an unused custom field) plus the operational condition that it applies only to admin-defined fields, not built-ins. It stops short of naming sibling alternatives (e.g. update_field for renaming) or explicit when-not-to-use guidance, so it lands just below the top.

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