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

Annotations already declare the tool read-only, idempotent, and non-destructive. The description adds useful behavioral context beyond those hints: the calendar-month window, per-currency grouping, and the ratio > 1 over-budget threshold. It does not contradict the annotations.

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?

One sentence communicates the scope, grouping, and interpretation of the output with no filler. The over-budget ratio definition is a concise and valuable addition at the end.

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 simple read-only report with zero required parameters, an output schema, and strong annotations, the description covers the essential invocation semantics: month, currency grouping, and ratio interpretation. Minor gaps like currency format are not blocking since currency is optional.

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 documents 'month' format and default, but 'currency' has no description, leaving 50% schema coverage. The phrase 'per currency' clarifies that currency is a meaningful grouping/filter dimension, but it doesn't explain the currency format or what happens when the parameter is omitted.

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 a budget-status report: it returns budgets with category/sub-category consumption for the current calendar month, per currency, and defines what an over-budget ratio means. This distinguishes it from generic spending tools like spending_summary or spending_trend, though it doesn't name them or use an explicit imperative verb.

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?

No guidance is given about when to use this tool rather than alternatives such as spending_summary or set_budget. The intended use is inferable from the name and content, but the description provides no explicit usage context or exclusions.

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