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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the write/destructive nature is known. The description adds genuine value by stating it replaces the existing card with the same product_key (an upsert-clobber), but omits whether unspecified fields are wiped, auth requirements, and the merge_keys behavior implied by the schema.

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 tightly-worded sentence with the replacement constraint front-loaded and no filler. Appropriately sized, though it is arguably too terse given the 7 undocumented parameters it must compensate for.

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 7-parameter destructive mutation with no output schema and 0% schema description coverage, the one-sentence description is not complete enough. It lacks field semantics, merge/merge_keys behavior, and required-field guidance needed to invoke the tool correctly.

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 largely does not. Only product_key is indirectly referenced; display_name, merge_keys, funnel_events, decision_rules, and connection_context are undocumented anywhere, leaving an agent unable to populate the required display_name meaningfully.

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?

Clear verb+resource: 'Save AdsAgent-owned product-card metadata', specifying it operates on AdsAgent-owned cards. It even discloses replacement semantics ('replacing any existing card with the same product_key'). However, it does not differentiate against the sibling google_ads_product_card_update, so an agent cannot tell save-vs-update apart from the text.

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 when-to-use guidance is given. With siblings product_card_update, product_card_delete, and product_cards_list present, the description never states when save is preferred over update or how they differ. The replacement clause is a behavioral note, not usage routing.

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