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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds genuinely new behavioral context: data is populated by a daily cron, so freshness is bounded to one day, and the response contains both history and a latest snapshot. It stops short of stating pagination or what happens if an account was only recently connected.

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 short sentences with the resource stated first and the return shape second; nothing is wasted. Minor redundancy: 'connected account' is repeated as 'connected social account' in the next sentence.

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, the description carries the burden of explaining the return payload and does so ('daily follower-count history ... plus the most recent snapshot'). Combined with the cron-freshness note, an agent has enough to call it correctly; only freshness edge cases and account prerequisites are absent.

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%, so the schema already documents both 'days' (default 30, clamped to [1,365]) and 'accountId'. The description only adds that the series is daily, which lightly clarifies how 'days' is interpreted, but adds no syntax or format detail beyond the schema. Baseline 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 (daily follower-count history for a connected social account) and a concrete output (history plus most recent snapshot). It is clear what the tool does, though it never contrasts itself with adjacent tools like getAccountHealth or getAnalyticsOverview, which an agent might reasonably consider for the same goal.

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 gives a use case ('tracking growth over time without scraping public profile pages'), which is implied guidance rather than an explicit when/when-not rule. No alternatives are named and no prerequisites (e.g., the account must be connected and cron-populated) are stated as conditions for choosing this over getAnalyticsOverview.

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