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

Annotations already declare destructiveHint=true, but the description goes further by specifying exactly what is destroyed ('clears it from them' on cards that use the option) and, more importantly, the two-phase semantics: without confirm:true nothing changes and the result is a preview. That dry-run/preview behavior is not derivable from any annotation or schema field and is the single most important thing an agent needs before invoking this tool.

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 sentences, no filler. The mutation is stated first and the confirmation/preview mechanic follows immediately, so the highest-risk fact is not buried.

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 four-parameter destructive mutation with no output schema and thin schema coverage, the description covers the critical gaps: what the operation does, what data it can destroy, and the confirm gate on the destructive path. It does not say whether name and options are independently optional or what errors look like, which keeps it out of 5 territory.

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 only 25% (confirm is the only documented property), so the description carries real weight. It explains what name does (rename), what options does (select field options), and reinforces the confirm preview semantics beyond the schema text. fieldId is left unexplained, but its meaning is unambiguous from the name.

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 names a specific verb pair and resource: 'Renames a custom field or changes a select field's options.' That is enough to separate it from create_custom_field and delete_custom_field in the sibling list without opening a schema. It stops short of naming a sibling or stating scope boundaries, which is what a 5 would require.

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 the condition under which the destructive path applies ('Removing an option that cards use') and the required flag ('which needs confirm: true'). No alternative tools are named and there is no when-not-to-use guidance, so it falls short of a 5.

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