Arrears for a month

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

Annotations already declare a safe read (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the bar is lower. The description still adds meaningful behavior: an authorization requirement ('Staff only'), the ordering guarantee, inclusion of a building total row, and the today-based cut-off for the current month.

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?

Three short sentences, front-loaded with the core definition, then audience, then the default-month edge case. No filler and every clause carries information.

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 does the work of describing the return set (ordered units plus a building total), which is the main thing an agent needs. It leaves the specific fields of each row implicit, but the inclusion of the authorization and cut-off details makes it comfortably complete for a one-parameter read tool.

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?

There is a single optional parameter and schema description coverage is 100%, so the schema already documents the YYYY-MM format and the omit-for-current-month default. The description only reinforces the current-month semantics (cut-off is today), which is a small addition beyond the schema; baseline 3 applies.

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 specific resource (units with an overdue balance at month end) and even defines the metric precisely as charges due minus payments made. The 'largest first, with the building total' clause pins down what it returns, which clearly separates it from the sibling unit_balance (single unit) and upcoming_bookings.

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?

Gives real usage context: 'Staff only' constrains the caller, and 'For the current month the cut-off is today' tells the agent what happens when no month is passed. It does not explicitly route between this and unit_balance, but the scoping sentence makes the distinction inferable.

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