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

Annotations already declare readOnlyHint=true, openWorldHint=true, and idempotentHint=true, so the safety profile is covered. The description adds the aggregation level and the metric set, which is useful, but says nothing about auth needs, rate limits, or result size/pagination for an open-world fetch.

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, zero filler, with the scope and metric list front-loaded and the sibling routing deferred to the end where it belongs. Every clause earns its place.

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-only aggregation call with no output schema, enumerating the returned metrics plus the per-ad alternative gives the agent nearly everything needed to select and invoke it. The remaining gap is result granularity/pagination behavior, which is minor against fully-documented parameters and safety annotations.

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 100%, so the schema already documents profile, date range, campaign_ids scoping, and ad_account_id fallback behavior ('omit to use the first ad account'). The description adds only the word 'account-level', which does not go meaningfully beyond the schema, so baseline 3 applies.

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?

Names a specific verb (Fetch) and resource (account-level LinkedIn Ads performance) and enumerates the metrics returned (spend, impressions, clicks, CTR, leads, demographics). It also explicitly demarcates itself from get_ad_performance_breakdown by scope (account totals vs per-ad detail), so an agent can distinguish the two without opening either schema.

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?

States a clear use case (setting paid reach/cost against organic profile output) and routes to the alternative tool for per-ad granularity. It stops short of stating preconditions or exclusions (e.g. that a LinkedIn Ads connection must exist), but the alternative and scope are explicit.

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