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

Beyond the readOnlyHint/idempotentHint annotations, it discloses a non-obvious latency profile (~15s due to background computation) and the exact error an unauthorized caller receives (APP_PERMISSION_DENIED). It also explains how members_new is derived differently for 7d/30d vs 90d, which is behavioral detail the annotations cannot carry.

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?

The metrics and admin restriction are front-loaded, and the sentences are dense with useful detail. The 'Admins only' statement is repeated at the end, which is a minor redundancy, though the second instance adds the error code.

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 explaining return fields, and it does so field by field (members_total, members_new, members_churned, MRR in USD). Combined with the latency and permission notes, an agent has everything needed to call 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 coverage is 100% and the enum is already documented, but the description adds real meaning by explaining that period changes the computation method for members_new rather than just a window size. That is semantics beyond the schema's 'Default: 30d' note.

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 opening sentence names the exact metrics returned (total/new/churned members and MRR) and the scoping dimension (a period). It is clearly distinguishable from siblings like list_members, get_group, and get_leaderboard, which do not aggregate revenue or churn.

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 an explicit precondition (admins only) and reiterates the failure mode, which tells the agent when the call will work. It does not explicitly contrast with alternative analytics sources (e.g. list_members or get_group), so it stops short of full when-vs-what-else guidance.

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