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tresor4k

macalc

calculate_exchange_margin

Detect hidden margins charged by money exchangers over the mid-market rate. Compare currency exchange offers by inputting the offered rate and mid-market rate to get the margin percentage.

Instructions

Detect the hidden margin charged by a money exchanger over the mid-market rate. Use to compare currency exchange offers. Inputs: offered rate, mid-market rate. Returns margin %. See list_bundles for related 'voyage' calculators.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
bank_rateYesBank/bureau rate
market_rateYesMid-market rate

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultNoComputed result. Object whose fields depend on the tool (e.g. {tax, marginal_rate, brackets} for tax tools, {volume_l, gallons} for volume tools).
formulaNoHuman-readable formula or method used (e.g. "I=P·r·t", "Magnus formula").
sourceNoAuthoritative source for the rule or formula (e.g. "Article 197 CGI", "NF DTU 21").
reference_urlNoLink to a calcul2 page documenting the calculation in detail.
Behavior3/5

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

No annotations provided, so description must disclose behavioral traits. It states returns margin %, implying a read-only calculation, but lacks details on auth, rate limits, or side effects. Acceptable but minimal.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences, front-loaded with purpose, then usage, inputs/outputs, and reference to related tools. No wasted words.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Simple calculation tool; description covers purpose, inputs, output, and related tools. Lacks formula or edge cases, but output schema likely provides return structure. Minor gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, baseline 3. Description adds value by mapping inputs to 'offered rate' and 'mid-market rate' and stating returns margin %, going beyond schema descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool detects hidden margin over mid-market rate and is used to compare exchange offers. It differentiates from siblings by specifying the margin detection and referencing 'voyage' calculators, but a similar sibling 'calculate_exchange_rate_margin' reduces clarity.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

States 'Use to compare currency exchange offers' and points to list_bundles for related calculators, but does not explicitly exclude alternatives like calculate_currency_exchange or when to use this versus other margin tools.

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

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