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

Annotations already declare destructiveHint=true and idempotentHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: attribute_key is permanent, used by filters/automations/bots, and cannot be changed afterwards - important for an agent deciding whether a key choice is safe. It stops short of explaining auth requirements or the consequence of the destructive flag.

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 compact sentences, front-loaded with the purpose before the parameter clarifications. Every sentence carries weight; no filler or padding.

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 high-parameter mutation tool with no output schema, the definition covers the safety profile (via annotations) and the key immutability well, but leaves most of the 8 parameters and any return/permission detail unaddressed. It is adequate but visibly incomplete.

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 only 13% across 8 parameters, so the description must compensate heavily. It only clarifies two: attribute_key (format and immutability - and the format is already in the schema pattern) and attribute_values ('for a list'). regex_cue, regex_pattern, attribute_description and the enum-bearing display/model fields get no explanation.

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 ('Create a new custom attribute'), which is unambiguous about the operation. It does not, however, differentiate itself from the sibling set (e.g. update_custom_attribute, delete_custom_attribute, create_a_custom_filter), leaving the agent to infer scope from the name alone.

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?

No explicit when-to-use guidance, no prerequisites, and no mention of the update/delete siblings or the list_custom_attributes counterpart. The agent gets no help deciding between creating versus updating an existing attribute.

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