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

Annotations (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false) already establish the safety profile and the description's 'Read-only.' is consistent with them. Beyond that it discloses behavior the annotations cannot: signals=true triggers additional lookups, audience signals are expanded to actual underlying lists with match size, and sub-1,000-member customer lists silently fail to serve.

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-loads the core purpose and the signals behavior, and every section is substantive. The editorializing about the 1,000-member minimum being 'the single most important configuration question' is slightly padded, but the paragraph still conveys actionable information.

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 read tool with an output schema available, the description goes beyond requirement by naming the returned fields (id, landing page, ad strength, status, per-asset resource_name). Nothing an agent needs in order to invoke it correctly is missing.

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 carries the burden, and it only fully documents `signals` (default, cost of extra lookups, what it adds). customer_id is never explained, and asset_group_id is only indirectly implied via 'Each group also reports its id'. Partial compensation merits the baseline 3.

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 ('Reads') and a precisely scoped resource (a Performance Max ASSET GROUP) and enumerates what it returns: creative content plus signals (audience signal, search themes). It distinguishes itself from the related mutation tools by naming update_pmax_assets and its remove_resource_names parameter.

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 clear routing guidance for the main decision point: signals=true is the default because the underlying first-party audience data is deemed critical, and signals=false skips the extra lookups. It also points to update_pmax_assets for removal/replacement. It lacks explicit guidance against other read siblings such as list_assets, but the mutation-vs-read boundary is well covered.

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