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

The annotations already declare destructiveHint=true, readOnlyHint=false, idempotentHint=false and openWorldHint=true, so the description's 'destructive write operation' adds nothing new. It does add one genuinely useful behavior beyond the annotations: field changes can affect existing records. It says nothing about reversibility, required authorization, or rate limits, so it stays at a middle score.

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 sentences, front-loaded with the action and endpoint, and the limitation caveat follows. Tight and readable, though the endpoint string is arguably redundant with the tool name.

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 13-parameter destructive mutation with no output schema and 46% schema coverage, the description is too thin. An agent gets no help on which of the many fields are actually updatable, what confirm does, or what the response contains.

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 13 parameters and only 46% schema description coverage, the description must compensate, and it does not. It never mentions the confirm requirement, the name/color/notes values being changed, value_type, filter_object_class, or the account_id/api_token auth parameters, leaving those to the schema alone.

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 (updates) and resource (a custom field definition) and even names the endpoint path /custom_fields/update/:custom_field_id, which clearly separates it from create_custom_field and delete_custom_field. It stops short of explicitly contrasting itself with those siblings, so it lands just below the top score.

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 only guidance is a 'Limitations' note that it is destructive and affects existing records. There is no indication of when to use this versus create_custom_field, update_enum_option, or delete_custom_field, and no stated prerequisites such as permissions or the confirm flag.

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