custom_fields_write

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

Annotations already declare destructiveHint=false, idempotentHint=true, and openWorldHint=true, so the safety profile is covered. The description adds a genuinely useful constraint (no deletion), but with 13 parameters it says nothing about what each action mutates, what is required per action, or auth/permission needs.

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 short sentences, front-loaded with the capability list followed by the action vocabulary and the exclusion. No filler or redundancy.

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?

The output schema exists, so return values need not be described, and the description does cover purpose and the action vocabulary. However, for a 13-parameter multi-action tool with zero schema documentation, the absence of any parameter-to-action mapping is a real completeness gap.

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 schema supplies only parameter names and defaults. The description usefully fills the one critical gap by naming the valid action_name values (the schema has no enum), but it leaves the other twelve parameters (field_id, fieldset_id, element, field_format, field_order_json, etc.) with no explanation of which action consumes them.

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+resource (create/update/associate/reorder fields and fieldsets) and enumerates the seven supported operations by name. It also explicitly excludes deletion, which cleanly separates it from custom_fields_search and delete_resource siblings.

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?

It tells the agent to drive the tool via explicit action_name values and states a clear negative boundary ('cannot delete fields or fieldsets'), which implicitly routes deletion elsewhere. It stops short of naming the alternative tool or explaining when to pick a specific action over another.

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