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

Annotations only cover the safe-read profile (readOnly, idempotent, non-destructive), so the description carries real weight beyond them: NET followers semantics, that history begins at connection time, that pre-connection days are null and total.partial flags mid-window connections, that other days are interpolated, that Instagram views only exist ~35 days back, and that scraped accounts may stop updating. This is rich, non-obvious behavioral context.

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 sentence and nearly every clause conveys needed semantics (view source rules, partial flags, best/worstDay gapDays). It is a dense, monolithic block that is hard to scan and could be split, but little of it is wasted for a tool this complex.

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 a complex analytics surface, the description fully explains return fields (followers, followersGained, isSnapshot, partial, views, viewsSource, postsPublished, reach, accountsEngaged, and the per-account aggregates) plus the notices field, leaving an agent nothing essential missing to interpret results.

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?

With 0% schema description coverage, the description must compensate and largely does: it documents days (7-365, default 30, ending today), from/to precedence and the 365-day span limit, and granularity (day default up to 90 days, week ending on `to`). brandId is never explained and platform is only implied by later mentions of Instagram/TikTok.

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 opening sentence gives a specific verb+resource and scope: follower growth and views per day/week for the brand's connected accounts, per account and in total. It is clear what the tool returns, but it never distinguishes itself from similarly-scoped siblings like get_metrics_daily, get_account_overview, or get_performance_summary.

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?

Usage is only implied through the window/granularity mechanics; there is no explicit 'use this when...' or 'instead of X'. An agent can infer intent from the detailed parameter prose, but no alternatives or exclusions are named.

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