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

Annotations already mark the tool as read-only and non-destructive, and the description adds meaningful behavioral context: frequencies are converted to monthly equivalents, duplicates are flagged per category with 2+ active recurrences, and the data is limited to financial information only. This goes well beyond what annotations provide and is especially valuable for setting expectations about what the tool cannot tell the user.

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, starting with the main scope immediately. The parenthetical frequency list is dense but useful, and the second sentence adds a clear limitation without unnecessary elaboration. Every sentence contributes value.

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 no-input tool with an output schema present, the description fully covers what the tool returns, how values are normalized, what aggregates are computed, and what information is deliberately absent. Nothing essential for calling the tool correctly is missing.

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 accepts zero parameters and the schema coverage is effectively 100%, so there are no parameter semantics for the description to clarify. The baseline of 4 applies because no parameters exist and the description does not need to compensate for undocumented inputs.

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 clearly identifies the resource: active expense recurrences (RecurringTransaction), and specifies the computed outputs: monthly-normalized values, total monthly committed amount, and duplicate categories. It is specific enough to be distinguished from generic listing tools, though it lacks an explicit verb such as 'returns' or 'lists'.

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 gives clear context for when to use the tool: to see all active recurring expense commitments with normalized monthly values and duplicates. It also explicitly states a when-not: it does not indicate service usage or whether a subscription is 'forgotten'. However, it does not name alternative sibling tools, leaving routing to inference.

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