A
licenseA
qualityD
maintenanceProvides access to currency exchange rates and conversion tools using the Frankfurter API, including latest rates, historical data, and time series from sources like the European Central Bank.
5
MIT
fx-converter-mcp
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@fx-converter-mcpconvert 100 USD to EUR"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
fx-converter-mcp
Real, current exchange rates and currency conversion, free, in one command.
pip install fx-converter-mcp # or: uvx fx-converter-mcpThen ask your agent: "convert 100 USD to EUR" or "what's the exchange rate between GBP and JPY?"
No API key. No signup. Free.
Tools
Tool | What the model sees it for |
| Convert an amount between two currencies at today's rate. "Convert 100 USD to EUR", "what's 50 GBP in yen". |
| Just the rate, no amount. "What's the exchange rate between USD and EUR?" |
Currency codes are 3-letter ISO (USD, EUR, GBP, JPY, ...) — major world currencies via the European Central Bank's reference rates, not every local or crypto currency.
Related MCP server: FX Currency MCP Server
Example
> convert_currency(100, "USD", "EUR")
{
"amount": 100,
"from": "USD",
"to": "EUR",
"converted": 86.55,
"rate": 0.8655,
"date": "2026-08-05",
"attribution": "Exchange rates by Frankfurter (frankfurter.dev), sourced from the European Central Bank"
}How it's free
This server is part of the Lulu Ads network:
tool results may carry one clearly labeled, disclosed sponsored data field
(never instructions, never hidden). That sponsorship pays the hosting, so the
conversion stays free. Fail-open by design — if the ads backend is slow, down,
or (as with a local install) has no credentials at all, the tools behave
exactly like an unmonetized server.
Run your own MCP? The same one-line integration is open to every publisher — getlulu.dev/publishers, 70% rev share.
Data
Exchange rates by Frankfurter (ECB reference rates, public domain). This project is not affiliated with Frankfurter or the European Central Bank.
Self-hosting over HTTP
pip install fastmcp lulu-ads httpx uvicorn
MCP_TRANSPORT=http FX_LOCAL_DEV=1 python server.py # serves http://localhost:8080/fx/mcpAvailable Tools
2 toolsconvert_currencyARead-only
Convert an amount from one currency to another using real, current
ECB reference exchange rates. Use for any "how much is X in Y"
question -- "convert 100 USD to EUR", "what's 50 GBP in yen".
from_currency/to_currency are 3-letter ISO codes (USD, EUR, GBP,
JPY, ...). Returns the converted amount, the rate used, and the date
the rate is from.
ParametersJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| amount | Yes | ||
| to_currency | Yes | ||
| from_currency | Yes |
Output Schema
ParametersJSON Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
A4.4/5.0
Behavior4/5
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, so the description doesn't need to restate safety. It adds valuable context: uses ECB reference rates, returns converted amount, rate used, and rate date. No contradictions.
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, then parameter/return details. No redundant words; every sentence adds value.
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?
For a simple 3-parameter tool with an output schema and read-only annotation, the description covers inputs, outputs, and data source. It doesn't mention error handling or unsupported currencies, but these are less critical given the tool's simplicity.
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 0%, so the description carries the burden. It explains from_currency/to_currency are 3-letter ISO codes with examples. Amount is self-explanatory from the context. This goes beyond the schema, though it could detail amount precision or edge cases.
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 clearly states the tool converts an amount between currencies using ECB reference rates, with specific verb+resource. It distinguishes from the sibling get_exchange_rate by focusing on conversation, not just rate retrieval. Examples solidify the purpose.
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?
Explicitly says to use for 'how much is X in Y' questions and gives example queries. It doesn't mention when not to use it or explicitly contrast with get_exchange_rate, but the usage context is clear and sufficient.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_exchange_rateARead-only
Look up today's exchange rate between two currencies, without
converting a specific amount. Use for "what's the exchange rate
between USD and EUR" style questions. from_currency/to_currency
are 3-letter ISO codes. Returns the rate and the date it's from.
ParametersJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| to_currency | Yes | ||
| from_currency | Yes |
Output Schema
ParametersJSON Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
A4.7/5.0
Behavior4/5
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark readOnlyHint=true, and the description adds that the tool returns both the rate and the date, and that parameters are ISO codes. No contradictions with annotations.
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 three concise sentences: purpose, usage example, and parameter/return details. No extraneous words.
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?
With only 2 simple parameters and an output schema, the description covers purpose, usage, parameters, and return value, making it fully adequate.
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?
The schema has no property descriptions (0% coverage), but the description clarifies that both parameters are 3-letter ISO codes, supplementing the bare 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 clearly states the tool looks up today's exchange rate between two currencies and explicitly notes it does not convert amounts, distinguishing it from the sibling convert_currency tool.
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 provides a concrete example of when to use it ('what's the exchange rate between USD and EUR'), and the phrase 'without converting a specific amount' indicates when not to use it.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
2 tool updates
v0.1.0- First observed
convert_currency - First observed
get_exchange_rate
TDQS
A4.6/5.0
Scored across 2 tools
Disambiguation5/5
The two tools have clearly distinct purposes: one converts an amount and returns the converted value, while the other simply returns the exchange rate without converting. There is no ambiguity between them.
Naming Consistency5/5
Both tools follow a verb_noun pattern: 'convert_currency' and 'get_exchange_rate'. The naming is consistent and predictable.
Tool Count5/5
Two tools is an appropriate scope for a focused currency conversion server. Each tool serves a distinct, essential function, and the count is neither too sparse nor excessive.
Completeness4/5
The tool set covers the core needs of converting currencies and fetching rates. A minor gap is the lack of a list of supported currency codes, but most users can work around this with ISO codes.
Maintenance
ActivitySlowing
ResponsivenessNo issues
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