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

Annotations declare readOnlyHint=false, destructiveHint=false and idempotent=false, so safety profile is covered. The description adds the crucial dry-run default: it previews unless confirm is true. It doesn't state that keywords are additive or that duplicates cause errors, but the preview behavior is the key non-obvious trait.

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 short sentences, front-loaded with purpose, then value context, then critical execution semantics. Every sentence earns its place.

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?

Covers purpose, domain context and preview behavior, but with 0% schema coverage, no output schema, and unannotated parameter meanings, the definition leaves required parameter semantics and the additive/replacement nature of keyword insertion undocumented. Adequate but with clear gaps.

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 0%, so the description partially compensates by documenting the confirm parameter's role (previews unless true). customer_id, campaign_id, keywords, and match_type are left with no prose semantics at all, which is a gap for a 5-parameter tool with 0% coverage.

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 (Add) + resource (negative keywords) + target (Google Ads campaign) + explicit outcome (stop wasted spend). Clearly distinguishable from sibling ads_add_keywords, which adds positive keywords.

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?

Provides usage context (usually highest-value change after a search terms report), which tells the agent when to reach for this tool. No explicit when-not-to-use or named alternative, but the domain cue is strong.

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