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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the primary behavioral profile is covered. The description adds two useful behavioral details beyond the schema: the call costs $0.10 and requires an API key. It doesn't mention pagination, rate limits, or the shape of the response, but with annotations covering safety, this is a reasonable contribution.

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 a single concise sentence that states the action and scope, followed by two parenthetical cost and auth notes. All content earns its place with no redundancy or filler. It is appropriately front-loaded with the core purpose first.

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?

Given the zero parameters and read-only annotations, the description covers the essential calling requirements: what it lists, the cost, and the API key requirement. However, it does not mention that an output schema exists or describe the return format, and it doesn't note whether all rows are returned or if there are implicit limits. For a list operation, this is adequate but not fully complete.

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 schema has zero parameters and 100% coverage, so there is no parameter documentation burden. With 0 params, the baseline is 4 per the rubric. The description adds no param detail, but none is needed since there are no parameters. It does not need to compensate for any schema gaps.

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 states a specific verb+resource: 'List expense/income/transfer rows.' This distinguishes it from other transaction-related tools like search_transactions, though it doesn't explicitly name alternatives. However, the title is essentially the same as the description, and the scope of 'rows' is somewhat vague. The description is clear but not strongly differentiated from siblings.

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?

The description implies it is a listing operation for expense/income/transfer rows, but it does not explicitly say when to use this tool vs alternatives such as get_expenses, search_transactions, or get_person_transactions. There is no mention of filtering, pagination, or date ranges, and it doesn't say when NOT to use it. Usage context is only implied by the verb 'List.'

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