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

Annotations already mark this as destructive and read-write, and the description adds substantial behavioral nuance: routeToken validity, placeholder token invalidity, the confirmation_required response without confirmWrite, preflight not being confirmation, and the scoping of counterparty confirmation. It also makes the destructive character concrete by explaining that nothing is written until confirmWrite is true.

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 dense but every sentence contributes critical workflow information. It front-loads the core purpose, then explains the routeToken lifecycle and the confirmation requirements in a logical order. No fluff or redundancy prevents it from being appropriately sized for a complex transactional 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?

Given 20 parameters, no output schema, and a two-phase write workflow, the description covers the most critical invocation semantics, including what happens without confirmWrite. It does not enumerate all mode-to-parameter mappings, but the schema covers those details, so the description is largely sufficient for correct invocation.

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 description coverage is 85%, so the schema already documents most parameters. The description complements it by explaining the workflow semantics around routeToken, confirmWrite, and confirmCounterpartyExplicit, including the preflight response. This goes beyond the schema's per-parameter descriptions.

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 uses a precise verb and resource: 'Creates a cash payment' and immediately names the three supported modes (supplier-ledger, bank-lodgement or analysed-expense). This clearly distinguishes it from sibling tools like brc_create_cash_receipt, brc_create_payment, and brc_update_cash_payment.

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 explains the operational context: it requires a routeToken from a matching action workflow and describes the preview/confirmation flow. It does not explicitly name alternative tools or state when not to use this tool, but the mode list and resource type give an agent clear context for selecting it.

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