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

Annotations already declare destructiveHint=true and idempotentHint=false, and the description usefully adds the required API-key scope. However, it never explains partial-update semantics (what happens to omitted fields), whether removing a field from the payload clears it, or any confirmation/reversibility behavior — gaps that matter for a mutation flagged destructive.

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, front-loaded with the operation and the mutable fields, followed by the auth scope. No filler, though the parenthetical field list is slightly redundant with the schema property names.

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 an 8-param mutation with destructiveHint and no output schema, the definition covers intent and auth scope but omits update semantics (partial vs. full replace), required-scope error behavior, and workspace/account selection implications. Annotations carry the safety profile, so this is adequate but clearly incomplete.

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 38%, and the description lists five of the eight parameters (name, description, emoji, color, isPrivate), adding minor value by framing them as the field's metadata set. It says nothing about the `account`, `workspace`, or `identifier` parameters beyond what the schema already documents, so it neither compensates for the coverage gap nor is empty.

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 (update) and resource (custom-field metadata) and enumerates the mutable fields (name/description/emoji/color/isPrivate), which clearly separates it from pm_create_custom_field or pm_delete_custom_field. It stops short of naming a sibling tool explicitly, so it lands at 4 rather than 5.

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 explicit when-to-use/when-not guidance or mention of alternatives such as pm_delete_custom_field or pm_create_custom_field. The only actionable context is the `custom_fields:write` scope note, which implies a write path but leaves the choice among CRUD siblings to inference.

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