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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuine scope context (values exist at three hierarchy levels) and explains the default fallback and length-limit counting behavior, but says nothing about return shape, volume, or pagination.

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 purpose, and no filler. The syntax/default sentences are useful but lean toward explaining downstream consumption of the data rather than the invocation itself.

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 single-parameter read tool with no output schema, the description does state what is returned (attributes and values) and at which levels, which is the key completeness question. It stops short of describing result format or pagination, but nothing critical is missing for a correct call.

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?

Only one parameter and schema description coverage is 100%, so the schema already fully documents customer_id, including the 'from get_accounts' provenance and format example. The description adds no parameter-level detail, making 3 the correct baseline.

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?

Clear verb+resource: lists ad customizer attributes and their values, with the scope specified as account, campaign and ad group level. No sibling tool covers customizers, so there is no confusion risk, but the description never explicitly distinguishes itself from the other 'get_*' listing tools.

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?

Usage is implied rather than stated: the description explains how to reference the returned attribute values in responsive search ad text, which hints at why you would call it, but gives no when-to-use guidance, prerequisites beyond the required customer_id, or alternatives.

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