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

Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description usefully adds the return shape ('daily snapshots') and the scoping by day count, but says nothing about pagination, data freshness/latency, rate limits, or permission requirements for a read-only analytics call.

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 tight sentences with the resource and return payload front-loaded and zero filler; nothing could be removed without losing information.

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 does the necessary work of stating what comes back (daily follower growth and engagement snapshots) and the time scoping. It is nearly complete for a read-only analytics tool; only freshness/latency and pagination behavior are unstated.

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 all three parameters are already documented, including the days default (30) and max (365). The description only echoes the day-window concept ('specified number of days') without adding format or semantics beyond the schema, so the 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 gives a specific verb+resource ('Get historical trend data for a social account') and names the concrete payload ('follower growth and engagement metrics over time'). It is clear enough to distinguish from a current-snapshot sibling like get_account_analytics by the word 'historical/over time', but it never names or contrasts that sibling 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?

Usage is only implied by 'over time' and 'historical' – an agent can infer this is for trend/backfill questions rather than point-in-time analytics, but the description gives no explicit when-to-use, when-not-to-use, or alternative (e.g. get_account_analytics).

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