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

Annotations already cover the safety profile (readOnly, non-destructive, closed-world), yet the description still adds substantial behavior: `growth` is null without a baseline, `needs_reconnect` flags broken connections, Instagram clamps windows to 30 days and surfaces this via `growth_window_days`, and YouTube/Facebook/Instagram deltas are fetched live while others come from daily snapshots. That is exactly the kind of data-quality caveat an agent 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?

Front-loaded with the resource and the question it answers, then layered with caveats in decreasing priority. It is dense rather than padded, though the snapshot-vs-live sentence is compacted enough to require a second read.

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?

There is no output schema, so the description carries the burden of return values and does so fully: it names each entry field, its nullability, and the one platform-specific shape deviation. An agent can consume and interpret the response without further documentation.

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 baseline is 3, but the description genuinely adds meaning: `previous` is defined as the last snapshot at or before `from`, and the platform-window interaction (Instagram 30-day clamp) affects how `from`/`to` behave. That goes beyond the schema's terse ISO-8601 notes.

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?

States a specific verb+resource and enumerates exactly what is returned: follower/subscriber/following/post counts per connected account plus in-window growth. It even notes the Google Business Profile variant, so the agent knows the shape changes by platform. It stops short of naming siblings like get_workspace_analytics or compare_instagram_accounts, so there is no explicit differentiation.

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 framing question "how are my followers trending" gives an unambiguous use case, and the Google Business carve-out clarifies a case where the tool still applies. There is no when-not guidance and no named alternative for overlapping analytics tools, which keeps it out of the 5 range.

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