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

The annotations are all present but largely negative, so the description still carries the burden of behavioral disclosure. The description does add useful context by describing the result composition and the free-tier limit, but it does not state whether the tool has side effects, consumes quota, or requires licensing. No contradiction with the annotations is present.

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 description is compact and front-loaded with the primary action ('Find charges that come back') followed by the useful output dimensions. The wording is slightly dense with several comma-separated output attributes, but there is no filler and every sentence earns its place.

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?

For a moderate-complexity tool with three well-documented parameters and no output schema, the description provides enough context: it names the grouping logic, output fields, and the free-tier limit. It does not spell out output formatting or edge cases, but the key invocation-relevant behavior is 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?

Schema description coverage is 100%, and each parameter already has a meaningful description, so the description is not required to repeat parameter details. The description adds no per-parameter semantics beyond what the schema provides; the free-tier note is a service limitation rather than parameter meaning.

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 description uses a specific verb and resource: it 'find[s] charges that come back' and identifies subscriptions/recurring debits grouped by counterparty and currency. It clearly conveys the tool's purpose without naming sibling tools, so it is clear but does not explicitly differentiate itself from siblings like transactions_search or statement_summary.

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?

There is no guidance about when to use this tool versus alternatives such as transactions_list, transactions_search, or statement_summary. The 'Free: 3 months, 5 charges' line is a limitation/constraint rather than a usage guideline, and no explicit when/when-not conditions are provided.

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