cash_register_balance

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

No annotations are provided, so the description carries the full burden. It transparently discloses a key edge case: returns { configured: false } when no cash-type bank account exists or its opening balance is not set. This is valuable behavioral disclosure beyond what the schema shows. Minor gap: doesn't describe auth/permission requirements or whether this is a read-only operation (though 'snapshot' implies non-mutating).

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?

Two sentences, tightly packed with relevant information: what data is returned, plus the critical edge-case return value. No filler or redundant phrasing. Well-structured for a snapshot tool.

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?

For a simple read-only snapshot tool with one optional parameter and no output schema, the description covers the core output fields and the main failure/configuration edge case. It's complete enough for an agent to select and invoke correctly, though a brief note on typical usage context (e.g., before closing the till) would strengthen it slightly.

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% but the parameter (companyId) is only lightly described ('Company UUID override (uses active company if not set)'). The description's main body doesn't add to the parameter, but given single optional parameter with clear schema description, minimal added semantics is acceptable. The description correctly scopes behavior to 'companyId' context implicitly.

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 a specific verb ('live snapshot') with a clear resource ('the till') and enumerates exactly what data is returned (opening balance, cash in/out, manual movements, current balance). It distinguishes from the sibling cash_register_ledger and cash_register_movements_list by being the aggregate balance view rather than a transaction list.

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 implicitly indicates when to use this tool: to view the current till state/balance rather than transaction history (ledger or movements list). However, it doesn't explicitly state when NOT to use it or name alternative tools for transaction-level detail, which sibling differentiation would require for a 5.

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