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

Annotations already declare destructiveHint=true, idempotentHint=false and openWorldHint=true. The description adds two pieces of genuinely new context: the operation is a preview by default and only executes when confirm is true, and 'the asset stays in the library' clarifies that the asset is unlinked, not deleted. It does not mention required permissions or scope of side effects on the campaign.

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?

Three short sentences, front-loaded with the core action and scope before the use case and preview caveat. No filler or repetition.

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?

No output schema exists, yet the description covers the key call-time facts: target scope, that the asset survives, and the preview/confirm gate. Only permission requirements and any limits on multiple unlinks are absent.

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 only 40%, so the description has to compensate. It explains confirm's preview semantics and the meaning of omitting campaign_id, but leaves field_type enum values and customer_id entirely undocumented and only gestures at asset_id via the schema note. Partial compensation for a five-parameter tool.

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 ('Unlink one extension asset') and precisely delineates scope: campaign-level by default, account-level when campaign_id is omitted. This clearly separates it from the sibling ads_add_extensions and from ads_list_extensions.

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?

Gives a concrete use case ('retire an old phone number or sitelink') and explains the campaign_id-omitted branch, which is effectively a condition for choosing account vs campaign scope. It does not name an explicit alternative tool or state when NOT to use it, so it stops short of a 5.

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