update_custom_field

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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the description is not carrying the full safety burden. It still adds genuinely non-obvious state semantics: archiving retains stored values while removing the field from contacts, and the operation is reversible via unarchive. It does not address partial-update semantics or what happens to omitted fields, which keeps it from a 5.

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?

Three front-loaded sentences with zero filler: the action first, then the parameter mapping, then the consequence of archiving. Every sentence earns its place and nothing is repeated from the annotations.

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 three-parameter mutation with no output schema and reasonable annotation coverage, the description supplies the important behavioral detail (archived-but-retained fields) and covers both optional parameters. Missing are partial-update semantics and any permission or error context, but these are secondary for this tool's complexity.

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 only 33% — 'label' and 'archived' have no schema descriptions — so the description must compensate, and it largely does by mapping each parameter to its effect ('change the label', 'archive and unarchive'). What it does not clarify is that supplying only one parameter leaves the other unchanged, which matters for a PATCH-style update.

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 (rename or archive a custom field) and enumerates the two supported mutations (label change, archive/unarchive), which is clearly distinct from create_custom_field and list_custom_fields. It stops short of explicitly naming a sibling to disambiguate against, but the purpose is 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?

Usage is implied rather than stated: the note that archived fields keep their values but stop appearing on contacts hints at why you would archive instead of delete, but there is no explicit when-to-use or when-not-to-use instruction, no mention of partial-update behavior, and no prerequisites such as permissions.

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