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

The description goes far beyond the readOnlyHint annotation by explaining the flattened row structure, the meaning of SummaryRow, the organisation-specific currency behavior, the end-of-month reporting quirk, and the non-calendar financial-year caveat. This is rich behavioral disclosure that protects an agent from subtle misreporting.

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 long but dense, and every major sentence adds operational value. It is front-loaded with purpose and safety, followed by output semantics and date/financial-year caveats. A few phrases, like the implementation-file reference, could be trimmed, but there is no real waste.

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?

With no output schema, the description compensates thoroughly by explaining result fields (columns, rows, rowType, currency, financialYear) and how to interpret them. It also addresses the most likely misunderstanding—calendar-year assumptions—making the tool safe to invoke and interpret without further probing.

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?

Although schema coverage is 100%, the description adds critical parameter meaning: date is interpreted as end-of-month, omitting date means today, and organisation is needed only for multi-organisation connections. It also connects the financialYear result field to parameter selection, which the schema alone does not convey.

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 opens with a precise statement: 'Balance Sheet report from Xero for the current organisation, as at a date.' It names the specific resource, the verb, and the temporal scope, and clearly distinguishes it from sibling financial-report tools like get_xero_profit_and_loss.

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 implies when to use the tool (when a balance sheet is requested as at a date) and clarifies its read-only nature, but it does not explicitly contrast it with alternative report tools or state when-not-to-use. There is useful operational guidance, but no explicit sibling-routing decision.

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