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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety and network profile is covered. The description adds real value beyond that: it names the live FX source (same as other forex _live tools), discloses the failure mode (available=false + error if no rate found), and explains why swapPerLotPerNight must be supplied manually (broker-set, no free live feed).

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 definition of the returned metric and the usage trigger, and the return-value sentence is compact. Slightly dense in the middle (FX source asides), but nearly every clause carries information an agent needs.

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?

No output schema exists, yet the description enumerates the extra return fields (accountCurrency, totalSwapAccount, fxRate, fxSource, available) and the error case, and explains what the non-live sibling already returns. Nothing an agent needs to call or interpret this tool 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 all five parameters are already documented, including the sign convention for swapPerLotPerNight. The description only reinforces that swapPerLotPerNight is a manual, broker-set input—useful but not additive over the schema's own detail. Baseline 3 applies.

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 output (total swap/rollover cost converted to account currency) and names the exact condition that separates it from its sibling workflow.run_forex_swap_cost (live FX conversion to a non-quote account currency). An agent can pick this tool apart from the non-live variant without opening either 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 an explicit trigger with a quoted user question ('how much will holding this position overnight cost me in my account currency?') plus the qualifier that it applies when the account currency differs from the pair's quote currency. It also implicitly routes to workflow.run_forex_swap_cost when no conversion is needed.

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