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

The paused-addition behavior is a genuinely non-obvious trait that annotations (readOnly false, destructive false, openWorld true) do not convey, and it materially changes what an agent must do next. It omits other behavioral facts such as duplicate handling, partial-failure semantics, and what identifiers come back.

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?

Two sentences, zero filler, with the most surprising and consequential fact (keywords arrive PAUSED) front-loaded after a one-line statement of purpose.

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 the biggest gotcha of a mutation tool, but for a write operation with no output schema and half the parameters undocumented, an agent still cannot predict default match type, duplicate behavior, or partial success handling. Adequate, not complete.

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?

The description adds no meaning to any of the four parameters. It never mentions match types, the nested match/cpc_bid fields, the 200-keyword cap, or the format of ad_group_id, even though schema coverage is only 50% and the nested keyword object is undocumented entirely.

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?

Names a specific verb and resource ("Add keywords to an ad group"), which cleanly separates it from read tools like google_ads_keywords and from google_ads_add_negative_keywords. It does not explicitly name those siblings, so differentiation is implicit rather than stated.

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?

Gives real workflow context: keywords land PAUSED when the campaign is running, and it routes the follow-up action to google_ads_set_status. It stops short of stating when to prefer this over sibling tools or what preconditions (ad group must exist, account selection) apply.

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