get_monthly_expenses

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

Annotations already declare readOnlyHint, openWorldHint, and destructiveHint. The description adds valuable behavioral context beyond those: data is scoped to São Paulo, decimal totals are returned as strings, and pending/ambiguous items are separated. This helps the agent interpret results correctly.

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: it states the core operation and date scope first, then adds two important output-behavior notes in a single extra sentence. Every part 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 read-only tool with an output schema, the description covers key invocation details: default month, date range usage, and output formatting. Still, it lacks sibling differentiation and leaves account_ids semantics unexplained, which is a noticeable gap for a tool with 4 parameters and 0% schema coverage.

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 0%, so the description must compensate. It explains the month and date range formats, which covers three of the four parameters conceptually, but it does not clarify the meaning or filtering behavior of account_ids.

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 clear verb and resource: returns monthly expenses. Adds useful scope details such as São Paulo, date format (YYYY-MM or range YYYY-MM-DD), and defaulting to the current month. However, it does not explicitly distinguish this tool from the sibling get_expenses_by_category.

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?

Provides practical usage guidance: month format, range format, and default behavior when no date is supplied. It does not name alternatives or exclusions, so the when-to-use vs sibling tools guidance is only implied.

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