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

With annotations already declaring readOnlyHint=false and destructiveHint=false, the description adds real behavioral context: it is a live-account write, the result is created in PAUSED state, and a confirm gate must be passed. It does not contradict the annotations; the write framing is consistent with readOnlyHint=false.

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?

One compact line, front-loaded with the most decision-relevant signal (WRITE to live account) and then the creation semantics. Every clause 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?

For a mutation tool with annotations and full schema coverage, the description covers the safety gate, default status, and bid unit. The one gap is return behavior — with no output schema, the agent isn't told whether an ad group id or resource is returned.

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 100%, so all six parameters are already documented including MICROS units and the confirm gate. The description mostly restates the schema's key facts (MICROS bid, PAUSED default, confirm:true) rather than adding new semantics, 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 ('Create an ad group under a campaign') and scopes it to the Google Ads domain, making it clearly distinct from google_ads_create_campaign and google_ads_update_ad_group. An agent can route to it without opening the schema.

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 operational prerequisites (requires confirm:true, created PAUSED) but never states when to use this versus update_ad_group or how it relates to campaign creation. Usage is implied rather than directed.

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