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

Annotations already cover the safety profile (readOnlyHint, destructiveHint=false, openWorldHint). The description adds real value beyond them: it names the external FX source (TrueFX/frankfurter.app) and discloses the failure mode (available=false + error when no rate is found), which an agent needs to handle the open-world dependency.

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 purpose, then usage, then return fields in three dense sentences; the output-field enumeration is long but earns its place given there is no output schema.

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?

With no output schema, the description compensates by enumerating the added return fields (accountCurrency, notionalAccount, marginAccount, fxRate, fxSource, available) and the error condition, so an agent knows both input and output contract.

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; the description only restates accountCurrency's role and lists output fields. Baseline 3 applies since the schema carries the parameter burden.

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 (notional and margin required for a forex position) and the exact scope qualifier (converted to account currency via a live FX rate). It also explicitly distinguishes itself from workflow.run_forex_margin_required, which it extends.

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 concrete trigger ("how much margin do I need in my account currency?") plus the selecting condition (account currency differs from the pair's quote currency), and names the non-live alternative for the other case.

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