set_account_currency

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

With no annotations, the description carries the full burden and does so well: it declares this is a mutation of 'Officer control-plane config', that it is 'protected and disabled by default', that the effective-currency change is blocked while specific state exists, and it names the exact error ('currency_change_blocked'). That is precisely the operational context annotations would ordinarily supply.

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-loads the verb and the empty-string behavior, then the guard conditions. The refusal sentence is dense with comma-separated conditions but every clause is substantive; no filler.

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 no explanation, and the description covers mutation scope, default protection state, inheritance fallback, and blocking conditions. Nothing needed to invoke this tool correctly is missing.

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 100%, so both parameters are already documented, and the description largely restates the inheritance behavior already present in the currency field. It adds one bit of nuance ('tracks no realized P&L when no tier is set') but no format, casing, or validation detail for the currency code, so the baseline 3 holds.

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 and resource ('Set or clear an account's own realized P&L currency') and immediately defines the clearing semantics, which separates it from sibling mutators like update_account or set_limit. An agent can tell exactly what this tool changes without opening the schema.

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 a clear usage context: passing an empty currency clears the override, and the description spells out the inheritance chain that then applies. It also enumerates the preconditions under which a change is refused (non-zero balance, position, cost-basis/P&L, halt, active order, Spot Funds P&L bound). It stops short of naming sibling alternatives such as update_account, so a 4 rather than 5.

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