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

With no annotations, the description carries the full burden for a write operation and discloses almost nothing behavioral. It does not say what happens on duplicate keywords, whether ad_group_id or campaign_id is required in practice, whether the call is idempotent, what errors look like, or what 'array POST' implies for batching.

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 a single front-loaded sentence with no filler. It is arguably too terse for a seven-parameter mutation tool, but that is a completeness issue rather than a conciseness problem.

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 mutation tool with seven parameters, no annotations, and no output schema, the description leaves significant gaps: required context (ad_group_id vs campaign_id), duplicate handling, batch semantics implied by 'array POST', and the effect on existing keywords are all unaddressed. It is not sufficient for an agent to invoke the tool confidently.

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%, so every parameter already has a description with defaults and constraints, making 3 the baseline. The description itself adds no parameter-level meaning beyond what the schema provides.

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 ('Add'), resource ('targeting keyword'), and destination ('to an ad group'), which clearly separates it from update_targeting_keyword, delete_targeting_keyword, and list_targeting_keywords. It does not explicitly name those siblings, and the plural tool name versus singular 'a targeting keyword' creates minor ambiguity about whether one or many keywords are added.

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?

There is no guidance on when to use this versus update_targeting_keyword or list_targeting_keywords, no prerequisites, and no exclusions. The '(CM API array POST)' note hints at the underlying API shape but does not tell an agent when this tool is the right choice.

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