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

Annotations only cover safety flags (readOnlyHint=false, destructiveHint=false, openWorldHint=false). The description adds real behavioral context beyond that: it runs a Google validate-only pass and returns a before/after draft with no mutation applied. It does not describe failure modes or validation error reporting, which keeps it short of a 5.

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 tight sentences, front-loaded with the action and scope, closing with the safety-relevant constraint. No filler.

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 13-parameter, low-documentation mutation-draft tool the description is on the thin side, but it does explain the prepare semantics and the returned before/after draft. With no output schema, a bit more on what the draft contains and how it transitions to confirm would be needed for a higher score.

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?

Only 1 of 13 parameters (customer_id) has schema documentation — 8% coverage — so the description must carry the load and largely does not. It hints at the entity_level values and that the update is 'typed', but gives no guidance on headlines/descriptions length limits, cpc_bid_micros units, status enum usage, or connection_context format.

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 (prepare) plus the four resource types it covers (campaign, ad-group, responsive-search-ad, keyword), which distinguishes it from narrower siblings like google_ads_budget_update_prepare or google_ads_bidding_update_prepare. It stops short of naming the confirm counterpart, so the distinction from its own paired sibling is left implicit.

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?

"No change is applied" implies this is the draft step of a two-phase flow, which nudges the agent toward google_ads_entity_update_confirm. But it never says to call confirm to apply, nor when to prefer a narrower update tool (e.g. google_ads_ad_text_update_prepare, google_ads_ad_status_update_prepare) over this general one.

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