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CurrencyGuard Guard Pricing

by com.currencyguard
OverviewDiscussionsAdmin

Historic Best/Worst FX Performance

get_historic_best_worst
Read-only

Analyze historic best/worst FX performance for a currency pair over a Guard's duration. Uses Bank of England historic rates. Returns a 'performances' array with 6 entries — BEST and WORST for each of three lookback periods (5, 10, 25 years). Each entry contains: type, lookbackYears, startDate/endDate, startRate/endRate, performancePercentage, startAmount, finalAmount, deltaAmount. For Guard-Pay: negative delta = cost decreased = BEST; positive delta = cost increased = WORST. For Guard-Receive: positive delta = receipt increased = BEST; negative delta = receipt decreased = WORST. Parameters must match the values used in the preceding price_guard call, including payReceive (PAY or RECEIVE).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
payReceiveYesMUST be the exact same payReceive value you used in price_guard (PAY or RECEIVE). Do NOT change it.
guardAmountNoGuard amount in base/home currency from the Guard quote (the guardAmount field from the price_guard response). Optional: leave it empty when there is no quote, and the tool uses today's indicative mid spot rate instead, so a risk question needs no price first.
foreignAmountYesAmount in foreign currency — MUST match foreignAmount from price_guard
guardCurrencyYesHome/base currency ISO code — MUST match guardCurrency from price_guard
settlementDateYesSettlement date in ISO format YYYY-MM-DD — MUST match settlementDate from price_guard
foreignCurrencyYesForeign currency ISO code — MUST match foreignCurrency from price_guard

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changed
    • changedInput schema / properties / guardAmount / description
      Previous value: -"Guard amount in base/home currency from the Guard quote (the guardAmount field from the price_guard response)"New value: +"Guard amount in base/home currency from the Guard quote (the guardAmount field from the price_guard response). Optional: leave it empty when there is no quote, and the tool uses today's indicative mid spot rate instead, so a risk question needs no price first."
    • changedInput schema / required
      Previous value: -[
-  "guardCurrency",
-  "foreignCurrency",
-  "payReceive",
-  "foreignAmount",
-  "guardAmount",
-  "settlementDate"
-]New value: +[
+  "guardCurrency",
+  "foreignCurrency",
+  "payReceive",
+  "foreignAmount",
+  "settlementDate"
+]
  2. Changed8 schema fields changed
    • addedInput schema / $schema
      Added value: +"http://json-schema.org/draft-07/schema#"
    • addedInput schema / properties / foreignAmount / exclusiveMinimum
      Added value: +0
    • addedInput schema / properties / foreignCurrency / maxLength
      Added value: +3
    • addedInput schema / properties / foreignCurrency / minLength
      Added value: +3
    • addedInput schema / properties / guardAmount / exclusiveMinimum
      Added value: +0
    • addedInput schema / properties / guardCurrency / maxLength
      Added value: +3
    • addedInput schema / properties / guardCurrency / minLength
      Added value: +3
    • addedInput schema / properties / payReceive / enum
      Added value: +[
+  "PAY",
+  "RECEIVE"
+]
  3. Changed1 schema field changed
    • removedInput schema / additionalProperties
      Removed value: -false
  4. First observed

TDQS

A4.1/5.0
Behavior4/5

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: the data source, the exact shape of the returned 'performances' array (6 entries across 5/10/25-year lookbacks), and the semantic interpretation of delta sign under Guard-Pay vs Guard-Receive. It does not discuss rate limits or auth, but for a read-only analytic tool that is acceptable.

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

Conciseness4/5

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

Front-loaded with the purpose, then moves through output structure and delta semantics in a logical order. It is somewhat dense, but each sentence (data source, array contents, PAY vs RECEIVE interpretation) carries information an agent needs. No filler sentences.

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?

With no output schema, the description helpfully enumerates the return array and each field, and the semantics of delta sign — so the agent knows how to interpret results. One minor gap: it insists parameters 'must match' the preceding price_guard call, while the schema notes guardAmount is optional and a risk question can be answered with no price first; the description does not reconcile this.

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

Parameters3/5

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

Schema description coverage is 100%, so all six parameters are already documented, including the payReceive enum and the price_guard matching constraints. The description reinforces the matching requirement and the PAY/RECEIVE semantics but adds little beyond what the schema already states. Baseline 3 applies when the schema does the heavy lifting.

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

Purpose5/5

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

States a specific verb and resource: 'Analyze historic best/worst FX performance for a currency pair over a Guard's duration.' It names the data source (Bank of England historic rates) and is clearly distinguishable from siblings like get_forward_rate, get_spot_rate, and compare_guard_with_forward, which address different computations.

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

Usage Guidelines4/5

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

It establishes a clear prerequisite: 'Parameters must match the values used in the preceding price_guard call, including payReceive.' This tells the agent how this tool sequences with price_guard. However, it names no alternative tools or explicit when-not-to-use conditions, so it stops short of full routing guidance.

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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