Custom field definitions

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

With no annotations, the description carries the full behavioral burden. The verb 'Lists' implies a non-mutating read and the parenthetical discloses the shape of what comes back, which is useful. But it says nothing about pagination, result size, authentication/permission requirements, or behavior when parent_type is omitted.

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?

A single front-loaded sentence with a compact parenthetical for return fields and an em-dash clause for the downstream purpose. No filler, no repetition of the title.

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 one-parameter read tool with no output schema, the description supplies the key missing pieces: what is returned and why an agent would call it. Remaining gaps (omitted-parameter behavior, pagination, result limits) are minor for a simple list operation.

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 description coverage is 0%, so the description must compensate. 'For matters or contacts' restates the Matter/Contact enum for parent_type in natural language, which is helpful, but it does not explain what happens when the optional parameter is omitted (both types returned? error?) or how the enum maps to downstream usage.

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 and resource ('Lists custom fields for matters or contacts') and even enumerates the returned definition fields (id, name, type, picklist options), so the agent knows this returns field definitions rather than values. No sibling tool covers custom fields, so confusion is unlikely, though the description does not explicitly contrast itself with any sibling.

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?

'Required to fill in custom_field_values' gives a real usage cue: call this first to obtain field IDs needed by value-setting operations. However, it names no alternative tool, no explicit when-not condition, and does not say whether the call is needed before creating vs. updating records.

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