Update custom field

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

Annotations already declare destructiveHint=true, idempotentHint=false, and openWorldHint=true, so the safety profile is covered. The description adds genuinely new context: that the call changes account state, that confirm=true is required, and the OAuth scope (`custom_fields:write`) needed. It stops short of saying what specifically is destroyed or how partial updates behave, but it adds real value beyond the structured fields.

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 short sentences with the core operation stated first, followed by the confirm requirement and the auth scope. No filler, no restatement of the title. Slightly terse given the tool's 7-parameter surface, but nothing is wasted.

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 7-parameter, destructive, non-idempotent mutation with no output schema, the description covers the confirm gate and auth scope but omits the PATCH-vs-update distinction and any explanation of what "changes account state" entails. An agent can call it, but the risk of picking the wrong sibling remains unaddressed.

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 86%, so the schema already documents account, confirm, payload, payload_file, and the IDs. The description adds no syntax, format, or interaction detail beyond that (e.g., it doesn't clarify how `display` at top level relates to the nested `payload.display`, or the mutual exclusivity of payload vs. payload_file, which only the schema states). Baseline 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?

States a specific verb and resource ("Update custom field"), so the agent knows exactly what operation is performed. However, the sibling list contains both `update_custom_field` and `patch_custom_field`, and the description makes no attempt to distinguish the PATCH semantics from the sibling's update semantics. Clear but undifferentiated.

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 one actionable usage rule ("requires confirm=true for the user-requested action"), which tells the agent when the call is legitimate. It does not say when to choose this over `update_custom_field`, nor does it describe what happens if confirm is omitted. Usage is implied rather than fully specified.

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