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

Goes well beyond the annotations (readOnlyHint=false, destructiveHint=false) by explaining that the call does not mutate anything yet, that the asset retains its ID and performance history across all links, and that the preview pins the current header/values so a concurrent Google Ads edit aborts the apply. That optimistic-concurrency detail is genuinely useful and not derivable from structured fields.

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 preview-returning nature is front-loaded in the first line, and the follow-up sentences each carry real information about identity retention and stale-edit handling. The trailing Google Ads API link is filler that doesn't earn 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?

With a full output schema, 100% parameter coverage, and annotations present, the description only needs to supply behavioral context — which it does through the preview semantics, ID/history preservation, and abort-on-stale-edit rule. Only the missing explicit apply-step routing keeps it from being 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?

Schema description coverage is 100% and each parameter (header, values, asset_id, customer_id) is already documented in the schema, including the 3-10 values / 25-character limits. The description only echoes the header/values pinning behavior without adding format or constraint detail, 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 ('Draft changing a structured snippet asset in place') and immediately flags the key output property ('returns a PREVIEW'). The word 'in place' plus 'keeps its ID' signals an update rather than a create, distinguishing it implicitly from draft_structured_snippets, though the sibling is never named.

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?

The draft/preview framing implies this is a proposal step that must be followed by an apply ('an edit in Google Ads before the apply stops it'), but the description never says explicitly when to pick this over draft_structured_snippets or how it relates to confirm_and_apply. Usage is inferable rather than stated.

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