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

Annotations already cover the mutation/safety profile, and the description adds meaningful context: negative keywords suppress ads for specific searches, removal is handled by a sibling, and creation returns resource names. It does not discuss duplicate handling or limits, but the added behavioral context is solid beyond annotations.

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?

The description is front-loaded with purpose and structured with Args/Returns, making it easy to scan. It is slightly less concise than ideal because the Returns line partly duplicates output-schema information, but there is little wasted text.

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?

Given a three-parameter mutation tool with an output schema and annotations covering safety, the description is complete enough to invoke correctly. It documents the nested keyword object format that the input schema leaves ambiguous and explains the operation's effect and return.

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 coverage is 0%, so the description carries the full burden and does so effectively: customer_id format is specified, campaign_id is identified, and keywords are explained as objects with text and match_type. It also gives allowed match types and the default, which the schema does not provide.

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?

The description states a specific verb/resource/scope: adding negative keywords to a campaign to block irrelevant traffic. It clearly distinguishes the operation from remove_negative_keywords and implies campaign-level scope versus sibling account/list variants.

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?

It gives useful context and names the inverse operation, remove_negative_keywords, but does not explicitly compare against sibling add tools such as add_account_negatives, add_to_negative_keyword_list, or attach_negative_keyword_list. The campaign scope is clear, but when-not guidance is limited.

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