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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered structurally; the description adds that results are 'raw' and roughly a year deep. However it states '~12 months of history' while the period parameter says the feed covers ~25 months, an internal inconsistency that muddies the scope claim. No mention of row counts, cost, or pagination beyond what the schema already says.

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 short sentences, front-loaded with the resource and scope, then the routing rule. No filler, and the contrastive 'to display, use transaction_list' clause earns its place by preventing a wrong tool choice.

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?

The tool has a rich schema and an output schema, so return-value detail is not needed here. The only real gap is the '~12 months' vs '~25 months' discrepancy, which leaves the agent unsure how far back results actually go.

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 100% and the period/limit/sort parameters are already richly documented in the schema (including the limit=0 totals trick and the startDate/endDate override). The description repeats category/merchant in prose but adds no new syntax or default behavior, so the baseline 3 applies.

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 and resource ('Raw transactions') plus the filter axes (by category or merchant) and the historical scope (~12 months), and explicitly contrasts itself with the sibling transaction_list. An agent can select it over transaction_list without opening either schema.

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?

Gives a clear use condition ('Numbers to reason with') and names the alternative for the other case ('to display, use transaction_list'). That routing is explicit, but there is no guidance on when neither applies or on the sort/period choices, so it stops short of full when/when-not coverage.

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