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

Annotations already declare readOnlyHint and openWorldHint, and the description adds real value on top: results are sorted by cost, cost is in account currency, the current day's data is incomplete, and conversions/leads/lead_form_opens have distinct meanings. It does not mention pagination or result limits, but for a read-only reporting call the disclosure is solid.

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?

Purpose is front-loaded in the first line, followed by the time-window rule, then field semantics — a logical order with no filler. It is somewhat dense and spends lines on return-field meanings that an output schema may also cover, but each line remains actionable.

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 two optional parameters, a 0% schema coverage, and an output schema present, the description supplies everything the agent still needs: the exact time window, sorting, currency, per-field meaning of the lead metrics, and the workspace fallback. Nothing required to invoke or interpret the call 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 description coverage is 0%, so the description must carry the load — and it does: `days` is defined as a window from today−N through today inclusive (today being partial), and `workspace` is a customer workspace slug that may be omitted when only one workspace exists. Only the default of 30 days is left to 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?

States a specific verb and resource: per-creative (individual ad) performance over the last N days, sorted by cost — clearly narrower than campaign-level reporting. It does not explicitly name the sibling it replaces (e.g. linkedin_campaign_performance or linkedin_performance_report), so differentiation is implied rather than stated.

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?

The description gives metric-selection guidance ("Bei Lead-Gen-Anzeigen leads auswerten") and explains when workspace may be omitted, which is useful usage context. However it never states when to pick this tool over linkedin_campaign_performance, linkedin_performance_report, or linkedin_audience_breakdown; the agent must infer the choice from the granularity.

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