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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds useful behavioral context about cost composition and breakdowns, but does not disclose potential limitations such as which cost categories are included/excluded or how the fiscal-year default behaves, so the additional transparency is adequate but not rich.

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 sentences deliver the core behavior, cost composition, breakdown dimensions, and a representative use case. No filler or redundancy; information is front-loaded and every clause 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?

Given a single optional parameter, full schema coverage, existing output schema, and safety annotations, the description is sufficient for an agent to select and invoke the tool correctly. It lacks explicit sibling differentiation, but the cost-type enumeration and period example fill most of the practical context gap.

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%, so the parameter is already well documented. The description reinforces the notion of a time period and gives a 'last quarter' example, but adds no new syntax, defaults, or constraints beyond what the schema already provides.

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?

Description clearly identifies the resource (all business costs), scope (period), and specific cost types (expenses, mileage, contractor bills), plus output dimensions (by-category, by-month). The example question 'what were my total costs last quarter?' makes the purpose immediately actionable and distinct from focused sibling summaries like get_expense_summary or get_mileage_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?

The description gives clear context for when to use the tool: when the agent needs total business costs for a period, with a concrete example. However, it does not explicitly state when to prefer alternate sibling tools such as get_expense_summary or get_cash_summary, so it stops short of full exclusionary guidance.

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