set_field_value

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

Goes well beyond the destructiveHint annotation by disclosing auth requirements ('requires whatever capability editing that entity itself requires, never a G00 capability') and the null-clears-value overwrite semantics. This is strong added context, though it doesn't cover side effects such as audit logging or the response shape.

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?

Three sentences, front-loaded with the core action, and each sentence carries substantive information. The 'a custom field is not a side door' clause is slightly editorial but reinforces the security constraint rather than wasting space.

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 mutation tool with no output schema and 0% schema coverage, the description supplies the essentials an agent needs: value typing, null-clearing, and capability requirements. The remaining gap — valid entityKind values and the idempotencyKey contract — is moderate but not disqualifying.

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?

With 0% schema description coverage the description must carry the load, and it does explain the most important parameter (value) richly: integer Rappen for money, ISO-8601 for dates, one option for select, null clears. It says nothing about entityKind, entityId, fieldKey, or idempotencyKey, so several parameters remain undocumented.

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?

States a specific verb (Set) and precisely scoped resource (one custom field value on one record), including that validation is against the field type. An agent can distinguish this from sibling field tools like define_field, confirm_field, and list_field_values without opening any 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?

Provides clear operational context — validation rules and that passing null clears the value — which implicitly tells an agent when to send null. However it never names an alternative or an explicit when-not-to-use condition relative to siblings like define_field or the batch field tools, leaving selection guidance implied.

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