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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds real context the annotations do not: the call is free, requires an X-API-Key, defaults to USD, and is served from approve.moneytools.dev. It does not describe response shape or how pagination/limits behave, which is the remaining gap.

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?

Very compact, front-loaded with the resource and aggregations, then auth/cost/currency details. The telegraphic phrasing ('Totals, by supplier, by day and exceptions') is slightly harder to parse than a full sentence but wastes nothing.

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 should at least say what the totals/exceptions look like, and it doesn't. Auth, cost and default currency are covered, but time-window semantics and return shape are left unspecified for a reader with three optional parameters.

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 only 33% (only 'month' is documented). The description explains the currency default (USD) but leaves 'days' and 'month' ambiguous — it never says whether they are additive, mutually exclusive, or what the default reporting window is when neither is supplied.

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 resource (totals for payments relayed by the MoneyTools Pay Gateway) and the aggregations offered (by supplier, by day, exceptions). An agent can tell it is a spend/receipts ledger rather than a wallet report, but the description never explicitly contrasts it with siblings like ledger_wallet_report or plan_status.

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?

No when-to-use or when-not-to-use guidance, and no indication of how to choose between the 'days' lookback and the 'month' selector, or what an agent should do if it needs per-transaction detail instead of totals. Usage is only implied by the phrase 'for this API key'.

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