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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds that Google's performance label is returned for PMax assets and that IDs are surfaced, which is genuinely useful, but says nothing about scoping behavior when account vs campaign_id is supplied or about result volume.

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?

Two sentences with the verb and scope front-loaded and zero filler. The asset-type enumeration is long but earns its place by telling the agent which extension types are covered.

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 no output schema, the description carries the burden of describing returns and does so reasonably: IDs plus Google's performance label for PMax assets. Minor gaps remain around whether account-level and campaign-level assets come back in one call and what the default scope is.

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 100% and both parameters are documented in the schema, so the schema carries the load. The description does not clarify the optional campaign_id filtering behavior or whether omitting both parameters returns account-wide assets, adding no meaning beyond the schema.

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?

The description opens with a specific verb+resource ("List assets with IDs") and enumerates the asset types covered: sitelinks, callouts, snippets, calls, images, and Performance Max asset-group assets. It does not explicitly distinguish itself from the nearest read-side siblings such as google_ads_pmax_assets or google_ads_ads, so it stops short of a 5.

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?

"Use to find asset IDs before removing or replacing" gives a concrete precondition that routes the agent to the correct downstream tools (google_ads_remove_assets, google_ads_add_assets). It does not state what to do when the caller already has IDs, nor does it name the sibling to use if only PMax assets are wanted.

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