Monthly recurring revenue

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

Annotations already declare readOnly/idempotent/non-destructive, so the description's job is computational semantics — and it delivers: which subscription states count (active and past_due), how yearly/weekly/daily/multi-month prices and quantities are normalized, and that only currently-active discounts apply. This is meaningful disclosure beyond the safety profile, though edge cases like trials, paused, or canceled subscriptions go unmentioned.

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 the return shape and followed by the calculation rules. Every clause carries information — normalization, discount eligibility, minor units, and the no-currency-combining constraint all matter to correct interpretation.

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 must convey the return shape, and it does: MRR and ARR broken out per currency, in minor units, never aggregated across currencies. It stops short of stating the container format (map keyed by currency, list of rows) or behavior on zero data, but the substantive semantics are covered.

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?

The tool takes no parameters, so the baseline is 4. The description correctly signals the no-input nature by framing the result purely in terms of server-side computation.

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 the exact resource and scope: current MRR and ARR per currency. It is unambiguous what is being computed, but it never differentiates itself from the sibling revenue_summary, which an agent could plausibly pick for the same intent.

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 the word "Current," which suggests a point-in-time snapshot rather than a historical series. No alternative is named, and there is no explicit statement of when to prefer this over revenue_summary or get_churn.

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