List custom fields

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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds the paid-plan requirement and workspace scope, but does not describe pagination, response shape, or other behavioral details; this is acceptable given the read-only annotation, though not rich.

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 resource and scope, with no filler. Each sentence adds distinct value: the first defines what the tool returns, and the second provides a crucial prerequisite.

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 read-only list tool with comprehensive schema and annotations, the description provides the essential definition and prerequisite. It lacks an explicit return-value description, but the title and tool family make the output obvious; no output schema leaves only a minor gap.

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?

The input schema is fully self-descriptive with 100% coverage, documenting all five optional parameters and their defaults/limits. The description adds no parameter semantics, but since the schema carries the burden, the baseline score 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?

The title 'List custom fields' and description 'Custom fields defined on the workspace' clearly identify the resource (custom fields) and scope (workspace), distinguishing it from sibling list tools. However, the description uses a noun phrase rather than an explicit verb, relying on the name/title for the action.

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?

The description states the workspace scope and adds a concrete prerequisite ('Needs a paid plan'), which tells the agent when the tool is available. It does not name alternatives, but none of the sibling tools are directly comparable for listing custom fields, so the guidance is sufficient.

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