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

Annotations already declare readOnlyHint/destructiveHint/openWorldHint, so the safety profile is covered; the description re-states it but adds genuinely new context: authentication requirement, per-school wallet scoping, live value reflecting orders/refunds, and a staleness warning. Only deduction is that the opening restates annotation-provided safety hints.

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?

Front-loaded with the read-only safety statement, then auth, scoping, currency, freshness, and usage routing in roughly priority order. Dense and every sentence carries information, though the read-only assertion partially duplicates the annotations.

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?

An output schema exists so return values need not be enumerated, yet the description still notes cents/formatting and liveness. Auth needs, scoping caveats, and the pre-payment use case are all covered for a zero-parameter 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?

Zero parameters, so the schema-based baseline is 4; there is nothing for the description to clarify. It does note the response is in cents and formatted, which is return-value context rather than parameter semantics.

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 verb+resource (get wallet balance) with tight scope: 'returns only the caller's spendable wallet balance at their active school'. The per-school scoping clause distinguishes it from sibling list tools like list_my_wallet_transactions and from generic balance reads.

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?

Explicitly tells the agent when to call it ('Call before pay_lunch_order_draft or register_for_event to confirm the user can cover the charge') and when not to ('not needed for read-only lookups'). Alternatives and the selecting condition are both named.

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