Folionomiq

What past crises did to this mix

past_crises

Read-onlyIdempotent

What past crises did to one portfolio held as it is today: 2008, 2020, 2022 and the others inside its price history. In: holdings. Out: for each crisis the deepest fall, the worst day and the days until the previous high came back; crises before a holding existed are named as not tested. Typical questions: 'How much would 2008 have cost me with 60% VTI, 20% VXUS, 20% BND?'; 'What did the 2020 crash do to this mix?'; 'Simulate a market crash on my portfolio.'. Instead: for a loss chosen by the reader ('what would it take to lose 30%?'), reverse_stress. For the whole record, return_history. Holdings in money give each fall in money; in percentages the falls are percentages. It does not recommend, predict or calculate tax.

Input Schema

Name	Required	Description
`base`	No	Currency code every figure is expressed in: USD, EUR, GBP, CAD… Default USD.
`units`	No	What the holdings' numbers are: 'money' (amounts in the base currency) or 'weights' (percentages or fractions). Omitted: holdings adding up to 1 or 100 are read as percentages, anything else as money, and the answer says so.
`holdings`	Yes	What is held: {ticker: number}, 1 to 100 holdings. Weights in any scale (60/20/20 or 0.6/0.2/0.2) or money amounts in the base currency (60000/20000/20000): `units` says which; without it, holdings adding up to 1 or 100 are read as percentages, anything else as money, which makes the falls come out in money. Tickers as the exchange lists them (VOO, VWCE.DE, EQQQ.DE, XAW.TO; 'CASH.USD' for cash). Example: {"VTI": 60, "VXUS": 20, "BND": 20}.

Output Schema

Name	Required	Description
`data`	No	Where the prices came from and what was missing or repaired.
`_fence`	Yes	What these figures are and are not: descriptive, no forecast, no advice. Repeat its sense when presenting the result.
`scenarios`	No	One entry per crisis.
`limited_by`	No	The holding whose short history limits the window.
`window_start`	No	First date all holdings have prices.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 22, 2026

changedInput schema / properties / holdings / description

Previous value: -"What is held: {ticker: number}, 1 to 100 holdings. Weights in any scale (60/20/20 or 0.6/0.2/0.2) or money amounts in the base currency (60000/20000/20000): holdings adding up to 1 or 100 are read as percentages, anything else as money, which makes the falls come out in money. Tickers as the exchange lists them (VOO, VWCE.DE, EQQQ.DE, XAW.TO; 'CASH.USD' for cash). Example: {\"VTI\": 60, \"VXUS\": 20, \"BND\": 20}."New value: +"What is held: {ticker: number}, 1 to 100 holdings. Weights in any scale (60/20/20 or 0.6/0.2/0.2) or money amounts in the base currency (60000/20000/20000): `units` says which; without it, holdings adding up to 1 or 100 are read as percentages, anything else as money, which makes the falls come out in money. Tickers as the exchange lists them (VOO, VWCE.DE, EQQQ.DE, XAW.TO; 'CASH.USD' for cash). Example: {\"VTI\": 60, \"VXUS\": 20, \"BND\": 20}."

addedInput schema / properties / units

Added value: +{
+  "anyOf": [
+    {
+      "enum": [
+        "money",
+        "weights"
+      ],
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "What the holdings' numbers are: 'money' (amounts in the base currency) or 'weights' (percentages or fractions). Omitted: holdings adding up to 1 or 100 are read as percentages, anything else as money, and the answer says so.",
+  "title": "Units"
+}

Changed2 schema fields changedOct 22, 2026

changedInput schema / properties / base / description

Previous value: -"Currency every figure is expressed in (USD, EUR, GBP, CAD…). Default USD."New value: +"Currency code every figure is expressed in: USD, EUR, GBP, CAD… Default USD."

changedInput schema / properties / holdings / description

Previous value: -"What is held: {ticker: weight or amount}. Weights need not sum to one; amounts in the base currency are also accepted (then the crises are shown in money). 1 to 100 holdings. Tickers as the exchange lists them (VOO, VWCE.DE, XAW.TO; 'CASH.USD' for cash)."New value: +"What is held: {ticker: number}, 1 to 100 holdings. Weights in any scale (60/20/20 or 0.6/0.2/0.2) or money amounts in the base currency (60000/20000/20000): holdings adding up to 1 or 100 are read as percentages, anything else as money, which makes the falls come out in money. Tickers as the exchange lists them (VOO, VWCE.DE, EQQQ.DE, XAW.TO; 'CASH.USD' for cash). Example: {\"VTI\": 60, \"VXUS\": 20, \"BND\": 20}."

AddedSep 25, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Annotations already establish that this is a read-only, idempotent, non-destructive operation. The description adds meaningful behavioral context beyond that: it explains the output fields, notes that crises before a holding existed are labelled 'not tested', and states that the tool does not recommend, predict, or calculate tax.

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?

The description is front-loaded with the purpose and input/output shape, then adds examples, sibling routing, and scope caveats. Despite being fairly detailed, every element is useful for selecting and invoking the tool correctly.

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

Completeness5/5

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

Given the tool's complexity, the presence of an output schema, and rich annotations, the description is complete enough: it covers the scenario, input expectations, output meaning, limitations, and alternatives. Nothing critical for correct invocation appears missing.

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%, and the input schema already fully documents holdings, base, and units. The description reinforces that holdings drive the analysis and that money-based versus percentage-based holdings affect whether falls appear in money or percentages, but it adds little parameter syntax or meaning beyond the schema.

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?

The description states a specific analytical operation: showing what named historical crises did to a current portfolio mix using its price history. It distinguishes the tool from siblings by explicitly naming reverse_stress and return_history as alternatives for different questions.

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

Usage Guidelines5/5

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

It gives explicit usage cues through typical questions and clearly routes related needs elsewhere: reverse_stress for a chosen loss level and return_history for the whole record. This leaves little ambiguity about when to call past_crises versus its siblings.

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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