set_field_value

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

With no annotations, the description carries the full burden, and it does well by disclosing type-validation behavior (with concrete examples), the null-clearing side effect, and the capability requirement. This goes well beyond a generic 'sets a field' statement and warns against privileged misuse. It doesn't mention idempotency or error behavior, but the core hidden behaviors are surfaced.

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 packed sentences with no filler. The primary action is stated first, followed by critical validation details, then the null behavior, then the security caveat. Every clause earns its place, and the structure guides the reader from what to how to when-not-to.

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?

Given the complexity (multiple value types, null clearing, capability policy) and the absence of annotations/output schema, this description covers the most decision-critical aspects. It lacks explicit notes about idempotency and response shape, but those are less likely to cause misuse. For a mutation tool, it is notably more complete than typical.

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. It meaningfully explains the 'value' parameter (formats for money, date, select, and null semantics), which is the most complex parameter. However, it does not clarify the roles of entityKind, fieldKey, idempotencyKey, workspaceId, or entityId beyond what their names imply. The added value is partial but relevant.

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 states a specific verb ('Set'), a precise resource ('one custom field value on one record'), and adds essential constraints (validated by type, null clears). This clearly differentiates it from unrelated sibling operations and would let an agent understand exactly what the tool does without opening the schema.

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 gives a clear context for use (setting a custom field with type validation and clearing via null), and includes an important caveat about required capabilities ('requires whatever capability editing that entity itself requires, never a G00 capability'). It does not explicitly name alternatives or say when not to use this tool, but the context is strong enough that an agent would not confuse it with list/define operations.

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