ad_group_bid_preview

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

The description is consistent with the annotations: 'preview' matching readOnlyHint=true and destructiveHint=false, so no contradiction. It adds little beyond the structured hints though — no statement about whether the preview validates against budget caps or account constraints, and no mention of the preview-then-apply handoff, which is the behavior an agent most needs disclosed here.

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?

A single front-loaded sentence with no filler; the object of the operation and the key value fields come first. It is efficient, though its brevity is what leaves the workflow gaps above.

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?

An output schema exists, so return values need not be described, and the safety profile is covered by annotations. What is missing is exactly the context a preview tool requires: that it is a dry-run whose output must be applied via the operations tooling, and how it relates to the update/bid siblings.

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% with all five required parameters documented, so the baseline is 3. The description echoes 'decimal amount and currency', which slightly reinforces the format expectation but adds no constraint (e.g. currency must match the account's currency) beyond what the schema already states.

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: previewing an ad-group default bid update, with the two value-bearing fields (amount, currency) called out. It is distinguishable from campaign_bid_strategy_preview and keyword_bid_preview by resource, but it never clarifies how it differs from the closely-named sibling ad_group_update_preview, which plausibly also touches bids.

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 guidance on when to choose this over ad_group_update_preview, ad_group_cpa_cap_preview, or the other bid-related preview siblings. Critically for a *preview tool, it never says that producing a preview is only step one and that operations_apply (or operations_inspect) must follow to commit the change, so an agent has to infer the whole workflow.

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