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get_etf_performance

Read-only

Retrieve an ETF's period and calendar-year returns plus volatility, return per risk, and maximum drawdown by ISIN to assess past performance and risk.

Instructions

Returns and risk of an ETF from justETF.

    Returns are in the currency named in `currency` (EUR by default).
    Past performance does not predict future results.

    Args:
        isin: ETF ISIN.
        refresh: Bypass the 24h cache.

    Returns:
        `performance`: period returns (YTD, 1m, 3m, 6m, 1y, 3y, 5y, since
        inception) and calendar-year returns; `risk`: volatility (1/3/5y),
        return per risk and maximum drawdown. Or an `error`.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "isin": "<isin>"
    },
    "name": "get_etf_performance"
  }
}

Input Schema

Name	Required	Description	Default
`isin`	Yes
`refresh`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 27, 2026

TDQS

A3.7/5.0

Behavior4/5

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

Annotations already declare readOnlyHint and openWorldHint, yet the description still adds real operational context: responses are cached for 24h and `refresh` bypasses that cache, values are denominated in a stated currency, and failures surface as an `error` field. The boilerplate 'past performance does not predict future results' line adds nothing an agent can act on, which keeps it from a 5.

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?

Purpose and denomination are front-loaded, and the Args/Returns sections are easy to scan. The disclaimer sentence is filler that does not earn its place.

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?

There is no output schema, and the description compensates by enumerating both the `performance` payload (YTD through since-inception returns plus calendar years) and the `risk` payload (volatility, return per risk, max drawdown) along with the error case. Only the phantom `currency` reference and missing ISIN format keep it from being fully self-sufficient.

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 0%, so the description must carry parameter meaning; it does explain `refresh` well (bypass the 24h cache) and labels `isin` minimally. However, it references a `currency` parameter that does not exist in the schema, which actively misleads an agent trying to control denomination, and ISIN format/length is never specified.

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?

States a specific verb and resource — returns and risk metrics for a single ETF identified by ISIN — which is enough to distinguish it from generic siblings like get_price_history or get_etf_holdings. It does not, however, explicitly contrast itself with the nearest sibling get_performance_stats, so an agent must infer the boundary.

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?

Usage is only implied by the resource named (an ETF, by ISIN). There is no explicit statement of when to reach for this tool versus get_performance_stats, compare_etfs, or get_etf_profile, and no prerequisites or exclusions are given.

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