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

Annotations already establish readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuinely new behavioral context: the output is an interactive dashboard, it includes period-over-period change, a daily trend and a per-campaign breakdown, and it should be summarised rather than recited. That output-shape disclosure matters because there is no output schema.

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: the first front-loads the metric inventory, the second sets the presentation expectation. Every clause carries information and there is no filler, though the metric list is dense enough that it reads as a run-on.

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 seven optional parameters, no output schema and no required fields, the description carries the burden of telling the agent what comes back, and it does so thoroughly (metric set, comparison period, trend, campaign breakdown, dashboard format). The only gap is routing guidance against the many adjacent Snapchat reporting siblings, which the description leaves unaddressed.

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%, and the enum parameters (detail, date_range, language) already carry explicit guidance including the LAST_30_DAYS default and the 31-day cap. The description adds no syntax, format or scoping detail beyond the schema, so the baseline of 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?

The description names a specific resource (Snapchat Ads dashboard) and enumerates the metrics it returns: spend, results, cost per result, swipes, impressions, purchase value, ROAS, change vs previous period, daily trend and per-campaign breakdown. That is far more specific than a name restatement. It does not explicitly differentiate itself from sibling reporting tools such as snapchat_breakdown or snapchat_campaigns, which keeps it out of 5 territory.

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 a presentational instruction ('summarise instead of repeating every number'), and the schema's detail enum supplies the summary-vs-full decision rule. However, it never says when to choose this dashboard over snapchat_breakdown, snapchat_campaigns or snapchat_ads, so the agent must infer the boundary from the sibling names alone.

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