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

Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=true. The description adds useful behavioral context: the Upper plan feature dependency and the underlying GET endpoint, while also clarifying the shape of the returned custom-field slots.

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?

The description is two tight sentences that front-load the resource and then add the plan prerequisite and endpoint. Every part contributes useful information without repetition.

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 zero-parameter read tool with no output schema, the description sufficiently explains what is returned: five custom-field slots with type, label, enabled, and required attributes, plus their enabled status. It also notes the plan-level prerequisite.

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?

This tool has zero parameters, so the baseline is 4. The description does not need to explain parameter meaning, and the empty schema is fully consistent with a workspace-level getter.

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 specifically identifies the resource as the workspace's five stop custom-field slots (custom1-custom5) and names the attributes returned. This clearly distinguishes it from sibling tools like upper_get_capacity_fields and upper_get_optimization_status.

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 by the resource description, and the description adds the important prerequisite that the Custom fields feature must be enabled in the Upper plan. However, it does not explicitly state when to call this instead of related getter tools or what workflow it supports.

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