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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses real behavioral traits: today's data is incomplete, daily values are retained only 6 months while monthly values persist longer, older daily requests are rounded to month boundaries, and an invalid campaign id raises campaign_not_in_account. That is exactly the kind of context annotations cannot carry.

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 and the body is organized as labeled lines (level:, date_from/date_to:, granularity:, campaign_ids:, workspace:), so it scans well. It is dense and long for a single report tool, but nearly every clause carries operational information rather than filler.

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 7-parameter, zero-required reporting tool with an output schema, everything an agent needs is present: level selection, date defaulting, granularity, filtering limits, workspace resolution, retention caveats, and the per-row return fields. No gaps remain that would cause a mis-invocation.

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 carries the full burden and does so: level enum values, granularity values (ALL/DAILY/MONTHLY/YEARLY), date format and defaulting logic, the 20-item cap and account constraint on campaign_ids, and workspace being optional when only one exists. Even the `days` fallback is covered.

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 first sentence states a specific verb and resource (LinkedIn performance for a freely selectable period) and enumerates the four supported levels plus the optional time series. It never names the sibling reports (linkedin_campaign_performance, linkedin_creative_performance, linkedin_audience_breakdown), so the agent must infer that this is the generic multi-level variant rather than a specialized one.

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?

Concrete guidance is given: use level=account for account totals instead of summing campaigns, dates are inclusive, omitting dates falls back to the last `days` days, campaign_ids must belong to the workspace ad account. No explicit when-not or sibling alternative is mentioned, which keeps it out of 5 territory.

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