Describe custom fields

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

Beyond the readOnlyHint annotation, the description discloses a critical behavioral quirk: custom-field values are keyed by numeric id, not display name, and using a name as a key is silently accepted with 200 but stored nowhere. This is exactly the kind of non-obvious behavior that prevents an agent from making a subtle mistake.

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 sentences with no filler. It front-loads the purpose and return fields, then adds the essential behavior warning. Every sentence earns its place.

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 read-only listing tool with one optional parameter, the description is complete: it names the resource, lists the output components, and flags the keying gotcha. The absence of an output schema is mitigated by the explicit statement of what is returned, and the readOnlyHint annotation covers safety expectations.

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 has 100% description coverage and already explains appliesTo in detail, including the 'employees' example and the instruction to call without an argument first. The tool description itself adds no additional parameter semantics beyond the schema, so the baseline 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 description uses a specific verb ('List'), names the resource ('organization's custom fields'), and specifies what is returned: id, object, and options. It clearly distinguishes this from siblings like productive_describe_resource, which would describe a resource's schema rather than enumerate custom fields.

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 implies its usage context clearly: call it to list custom fields and understand how values are keyed. The input schema adds explicit guidance to call without an argument first and then pick from appliesToValues, which is practical usage direction. It does not explicitly name alternative tools or state when not to use it, so it stops 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.