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

Annotations already declare readOnlyHint=true, so 'Read-only' is redundant. The 'Pro' tag does add plan/entitlement context not present in annotations, and the returned fields are disclosed, but pagination behavior and handling of the undocumented limit parameter are not addressed.

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, each carrying distinct information (scope, downstream use, safety/plan) with no filler and the core purpose front-loaded.

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 usefully enumerates return fields and downstream consumers. For a two-parameter read-only list tool that is nearly sufficient; only limit/pagination semantics are 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 description coverage is 0%, so the description must carry parameter meaning. It implies meta_account_id via 'an ad account's' but says nothing about the limit parameter (default page size, max, or whether pagination applies), leaving half the parameters undocumented.

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 and resource ('List an ad account's custom and lookalike audiences') and even names the fields returned (size, type, readiness). It is clearly distinct from siblings like create_lookalike_audience or delete_custom_audience by the list verb, though no sibling is named explicitly.

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 workflow cue: the returned ids feed create_campaign's customAudiences / excludedAudiences. That is clear context for when to call it, but there are no exclusions or alternative-tool comparisons.

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