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

Annotations already establish read-only, idempotent, non-destructive behavior, and the description adds substantial context beyond that. It explains what the result contains, how to interpret favorable variances, what hasBudget false means, where budgets are set, and that figures must be quoted from the result only.

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 definition is front-loaded with the core purpose, then provides useful trigger phrases, return semantics, and the crucial hasBudget caveat. Despite being detailed, every sentence supports correct tool selection or interpretation.

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?

There is no output schema, but the description sufficiently explains the return structure and interpretation rules. Combined with the read-only annotations and fully documented input schema, an agent has what it needs to call and explain this tool correctly.

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 coverage is 100%, so the schema already documents company, to_month, and from_month with formats and defaults. The description only indirectly connects month/quarter/year phrasing to the period parameters, so it adds little parameter-level meaning beyond the schema.

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 the resource and purpose directly, then specifies the exact returned fields: budget, actual, variance, variance percent, totals, and net profit for income, cost of sales, and expense accounts. This clearly distinguishes it from general P&L or balance-sheet tools.

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?

It gives explicit trigger phrases such as 'against budget', 'over budget', 'budget variance', and 'are we on track,' plus month/quarter/year comparison guidance. It also states the important exception: when hasBudget is false, say so and point to /reports/budget rather than presenting zeros.

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