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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered and the description is not burdened with it. What the description adds beyond structured data is the cross-tool contract: the returned resource_id format ('campaignId~criterionId') is explicitly the value accepted by remove_entity, which is genuinely useful linking behavior not encoded in the schema.

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-loaded with purpose, then return shape, then a reference link; no sentence is redundant. The trailing Google Ads API URL is marginal filler but short enough not to dilute the structure.

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 need not be enumerated in prose (though the description helpfully does), and both parameters are fully described in the schema. The only meaningful gap is explicit disambiguation from the negative-keyword-list tools that share the same domain vocabulary.

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% for both optional parameters (campaign_id, customer_id), so the schema fully documents filtering and defaulting behavior. The description adds nothing about parameter syntax or empty-value semantics beyond what the schema states, so the 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?

States a specific verb and resource ('List existing negative keywords') plus scope ('for a campaign or all campaigns'), so an agent knows what it returns. It does not, however, distinguish itself from the nearby negative-keyword-list siblings (get_negative_keyword_list_keywords, get_negative_keyword_list_campaigns), which address a different resource (shared sets) and could plausibly be confused with this one.

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 line 'reveals duplicates before new negative keywords are added' implies the check-before-write workflow with add_negative_keywords, which is real but indirect guidance. There is no explicit when-to-use/when-not and no sibling is named as an alternative, leaving the choice to inference.

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