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

Annotations already declare readOnlyHint/openWorldHint/destructiveHint, so the safety profile is covered. The description still adds real operational context beyond them: metrics are cached and refreshed about daily, the call is cheap, it is free, and accountsWithMetrics/accountsTotal plus capturedAt disclose that coverage may be partial or stale.

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 sentences, front-loaded with what the tool returns and scoped by cost/caching before the alternative route. The long metric enumeration is dense but each element is informative; no filler sentences.

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 takes on the full burden and discharges it by naming the return fields (views/likes/comments/shares/posts/followers, delta, per-day and cumulative series, coverage counters). An agent has enough to decide to call it and interpret the result.

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 0%, so the description must carry the single parameter, and it does enumerate the valid windows ('last 7, 30 or 90 days'). It does not state the default of 30 that the schema supplies, so it is good but not fully compensating.

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 first sentence names a specific verb+resource ('Roll-up of ALL your hosted / managed accounts' performance') and enumerates the exact metrics returned, so scope is unmistakable. It also draws an explicit boundary against get_social_analytics for single-account breakdowns, letting an agent distinguish it from siblings without opening schemas.

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 states the period options, that it is served from cached metrics and cheap, and that it is free, plus an explicit alternative with a named parameter ('For one account's breakdown use get_social_analytics with source managed_account'). That is a complete when-to-use/when-to-use-something-else statement.

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