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

Annotations already flag destructiveHint=true and idempotentHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: it discloses the dry-run mode via confirm=false, and the non-obvious capability that this works on Google-hosted local actions the API otherwise refuses to change. It does not spell out the bidding impact of a demotion, but the added context is substantial.

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?

Front-loaded with the core purpose before the sibling comparison and parameter notes. It is dense and parenthetical-heavy, packing several clauses per sentence, but nearly every clause carries useful routing or parameter information rather than 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?

An output schema exists, so return values need no explanation. For a destructive, non-idempotent mutation tool the description supplies identification workflow, parameter meaning, dry-run behavior, and the special-case scope, leaving little an agent needs to call it 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 coverage is 0%, so the description must carry the load, and it does for most params: role values ('PRIMARY' biddable | 'SECONDARY'), category+origin as the goal identifier, campaign_id as an optional override, and confirm as dry-run. customer_id is left unexplained but is self-evident from the ecosystem.

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+resource ('Makes a conversion CATEGORY primary or secondary') and immediately differentiates from the sibling update_conversion_action by naming its legacy flag and the Google-hosted 'local actions' case it uniquely handles. An agent can tell exactly what this does and how it differs from adjacent tools.

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?

Explicitly says to 'run list_conversion_goals first' and gives the category+origin identification convention with two worked examples. It also states when to pass campaign_id (per-campaign override) vs omit (account-wide), and when to use this over update_conversion_action.

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