Campaigns using a brand list

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

Annotations already cover the safety profile (readOnlyHint true, destructiveHint false, openWorldHint true). The description goes beyond them by disclosing the row type behind the result (CampaignCriterion / BRAND_LIST) and decoding the `role` field semantics ('excluded' vs 'targeted'), which is real behavioral context an agent would not otherwise infer.

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?

Front-loads the one-line purpose before the technical detail, and the CampaignCriterion clarification earns its place. The trailing 'Google Ads API' URL is boilerplate padding that adds little, but the rest is tight.

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?

An output schema exists, so return values needn't be explained, yet the description helpfully clarifies the non-obvious `role` semantics. Combined with annotations and full schema coverage, an agent has what it needs to call it correctly; only pagination/volume behavior is left unstated.

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 100% and both parameters are documented in the schema itself (customer_id default, shared_set_id default-omitted behavior). The description's field list (campaign ID, name, status, criterion, role) describes outputs, not inputs, so it adds no parameter meaning beyond the schema. Baseline 3 applies.

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?

Specific verb+resource ('List which campaigns a brand list is attached to'), and it actively distinguishes itself from the sibling family by contrasting the attachment mechanism (CampaignCriterion of type BRAND_LIST vs CampaignSharedSet used by negative keyword lists). An agent can separate this from get_negative_keyword_list_campaigns and get_brand_lists without opening a schema.

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 context is clear: it reveals the reverse-lookup purpose (list -> campaigns), and notes that omitting the list ID returns all brand-list attachments in the account. It does not name an explicit alternative or a when-not-to-use case, but the surrounding detail about attachment semantics gives the agent enough to place it correctly.

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