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

Annotations already cover the safety profile (readOnly, non-destructive), so the description's real contribution is the partial-failure behavior: networks that did not respond are flagged and must not be presented as zero. That is exactly the kind of data-quality caveat an agent needs and cannot get from the 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?

Three tight sentences: metrics first, then the optional period constraint, then the data-quality warning. The PilotControl dashboard analogy is the only expendable phrase, but it usefully signals that this is an aggregate overview view rather than raw records.

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 and zero required parameters, the description carries the burden of explaining what comes back, and it largely does: metric categories, per-network breakdown, and handling of failed networks. It stops short of describing response shape or how figures are aggregated over the period.

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 coverage is 100%, so the parameters (from, to, brand_id) are already documented, including the brand-selection rule tied to list_brands. The description adds only the 366-day ceiling on the period, which is a useful but small increment over the schema baseline.

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 (brand-level summary) and enumerates the metrics returned: followers, reach, views, interaction, plus per-network evolution. It implicitly distinguishes itself from per-account siblings (get_account_stats, get_account_insights) by scoping to the whole brand across networks, though it never names those alternatives 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?

It states the period is optional and caps it at 366 days, which is actionable context for calling the tool. However, it gives no explicit guidance on when to prefer this over get_account_stats, get_account_insights, or get_post_stats, so the agent must infer the brand-vs-account split.

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