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

Beyond the readOnlyHint annotation, the description discloses important behavioral semantics: `total` is strictly liquid cash, owner funding and card balances are separate liabilities, each card has a `direction`, and balances are MYR-booked even for foreign accounts. This is substantial, practical behavior guidance that prevents common misuse and 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?

The description is front-loaded with the main numeric/computational answer and then expands into the important exclusions. It is dense and fairly long, but each rule contributes to correct interpretation of the output. A little tightening would improve it, but for a tool with a nuanced cash distinction structure, the length is justified.

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 at all, the description carries the responsibility of defining the return shape, and it does so effectively: `total`, `accounts`, `ownerFunding`, `cards`, `cardsOwing`, `direction`, and the relevant currency/booking behavior are all explained. There is enough detail for an agent to both invoke the tool and correctly present the result.

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 are zero parameters and the schema has 100% coverage by being empty, so the baseline of 4 applies. The description adds value by explaining the meaning of the conceptual result fields, but there are no parameter-specific semantics needed here.

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 opening sentence clearly states what the tool reports: current cash across every bank account and cash pocket, with GL balances and a grand total. Even though it uses a question-style phrasing rather than a firm imperative, it identifies the resource and scope precisely and separates it from forecast-type siblings by focusing on the right-now position.

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 clearly establishes when this tool is appropriate: whenever the agent needs the current cash position as booked in the GL. It also instructs how to treat returned values, such as reporting owner funding as a liability and card balances only as debt outside total. It does not, however, explicitly name alternatives like cash_forecast or business_snapshot, so it stops short of giving full when-to-use/when-not-to-use routing.

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