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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint, so the safety profile is fully covered and the description is not required to repeat it. The description adds scoping context ('per connected account over a period', implicitly a growth delta), but says nothing about granularity of the breakdown or limits imposed by the 365-day window.

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 short sentences, front-loaded with the resource and scope, no filler. The second sentence is slightly weakened by referencing an 'engagement' tool that does not appear among the siblings, but it is still compact.

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?

For a zero-required-param read tool with a fully documented single parameter and annotations carrying the safety profile, the description is nearly sufficient. The main residual gap is that the agent cannot tell how the per-account output differs from the other analytics tools, and there is no output schema to clarify the shape.

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?

There is a single parameter ('days') whose schema description already states 'Look-back window in days' at 100% coverage. The description's phrase 'over a period' echoes the same idea without adding format, timezone, or boundary semantics, so this is the baseline 3.

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 and metric set ('Follower counts and growth per connected account over a period'), which is more precise than the title alone. It does not, however, distinguish itself from the many analytics siblings such as get_audience_insights, get_platform_analytics, or get_analytics_overview, so the agent must guess which analytics surface this is.

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 second sentence implies a use case ('judge which platforms are worth investing in') and suggests pairing with 'engagement', which is usage context. But it names no sibling tool from the actual list and gives no when-not or exclusion criteria versus the other analytics tools, leaving the choice to inference.

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