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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is covered; the description still adds real value by disclosing that an existing card with the same product_key is destroyed rather than merged. Remaining gaps: whether unsupplied fields are wiped on replacement, and whether 'AdsAgent-owned' imposes an ownership restriction that would cause the call to fail on foreign cards.

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 wasted words; the replace semantics land before any filler. It is lean but doesn't pad, so the only issue is that it is arguably too terse for a 7-parameter mutation.

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 destructive 7-parameter mutation with nested objects (decision_rules, funnel_events) and zero schema description coverage, one sentence is not enough. An output schema exists so return values needn't be described, but the parameter and replacement-scope gaps dominate.

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 0% across 7 parameters, so the description must carry the burden and does not. Only product_key's role in matching is implied; display_name, merge_keys, funnel_events, decision_rules, and the connection_context pattern are entirely unexplained.

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 (Save) and resource (product-card metadata) and adds the upsert rule ('replacing any existing card with the same product_key'), which is more than a name restatement. However, it never distinguishes itself from the close sibling google_ads_product_card_update, which an agent will reasonably see as overlapping.

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 explicit when-to-use, when-not-to-use, or alternative routing is given. The replace/upsert behavior is implied, but nothing tells the agent to prefer product_card_update for partial edits or product_card_delete for removal, nor are any prerequisites stated.

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