Skip to main content
Glama
Sign In

Stablecoin Gateways

by com.stablecoingateways
OverviewDiscussionsAdmin

Currency Converter (ECB)

fx_convert
Read-onlyIdempotent

Currency converter (ECB reference rates): convert an amount from one currency to one or more others, e.g. 250 USD to EUR, GBP and JPY, at the latest European Central Bank rate or any day in the last 90 days. Returns the rate, converted amount and rate date for each target. 30 currencies. Reference rates, not transaction rates. Source: ECB. Signed receipt. Price: $0.001 per call via x402 (USDC on Base or XRP on XRPL). The response includes a provenance block (sg-provenance/1): each fact carries its source, source URL, retrieval time and limits; evidence only, no score, rating or verdict. Example arguments: {"from":"USD","to":"EUR,GBP,JPY","amount":"250"}.

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": {
      "from": "<from>",
      "to": "<to>",
      "amount": "<amount>"
    },
    "name": "fx_convert"
  }
}

Input Schema

NameRequiredDescriptionDefault
toYesComma-separated target currencies (ISO 4217), 1-10
dateNoRate date YYYY-MM-DD within the last 90 days; default latest
fromYesSource currency (ISO 4217)
amountYesAmount to convert

Output Schema

NameRequiredDescriptionDefault
dataNoConverted amounts and rates per target currency at the ECB rate date
receiptNoEd25519-signed, hash-chained receipt; verify free with the verify_receipt tool or POST /v1/verify-receipt. New receipts carry a signed `evidence` object: service_version, data_timestamp, validation, terms_version, terms_hash, provenance_hash.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changed
    • addedOutput schema / properties / data / properties / provenance
      Added value: +{
+  "description": "The response includes a `provenance` block (sg-provenance/1): each fact carries its source, source URL, retrieval time and limits; evidence only, no score, rating or verdict."
+}
  2. Changed1 schema field changed
    • changedOutput schema / properties / receipt / description
      Previous value: -"Ed25519-signed, hash-chained receipt; verify free with the verify_receipt tool or POST /v1/verify-receipt"New value: +"Ed25519-signed, hash-chained receipt; verify free with the verify_receipt tool or POST /v1/verify-receipt. New receipts carry a signed `evidence` object: service_version, data_timestamp, validation, terms_version, terms_hash, provenance_hash."
  3. Changed1 schema field changed
    • changedOutput schema / (root)
      Previous value: -nullNew value: +{
+  "description": "Paid result: { data, receipt }. Unpaid calls return an x402 PaymentRequired object instead (isError: true).",
+  "properties": {
+    "data": {
+      "description": "Converted amounts and rates per target currency at the ECB rate date",
+      "properties": {
+        "amount": {},
+        "conversions": {},
+        "cross_rates_derived": {},
+        "from": {},
+        "note": {},
+        "rate_date": {},
+        "requested_date": {},
+        "source": {},
+        "window": {}
+      }
+    },
+    "receipt": {
+      "description": "Ed25519-signed, hash-chained receipt; verify free with the verify_receipt tool or POST /v1/verify-receipt"
+    }
+  },
+  "type": "object"
+}
  4. First observed

TDQS

A4.6/5.0
Behavior5/5

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

Annotations already declare read-only/idempotent, and the description adds substantive behavior beyond them: per-call pricing via x402 (USDC on Base or XRP on XRPL), a signed receipt, and the shape of the provenance block plus its 'evidence only, no verdict' limits. That is exactly the kind of cost/auth/output-character context an agent needs before invoking a paid external call.

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?

The core capability and scope come first, followed by return shape, caveats, pricing and an example — a sensible front-loaded order. It is dense with parentheticals (provenance spec id, chain names) but nearly every clause carries actionable information; the provenance sentence is the longest and slightly over-elaborated for a converter.

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?

Even though an output schema exists (so return values needn't be explained), the description still sketches the per-target result and the provenance envelope, and it covers cost, currency count, date bounds and rate semantics. Nothing an agent needs to call this correctly is missing.

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%, so baseline is 3; the description earns above that by supplying a concrete example argument object that demonstrates the comma-separated multi-target 'to' format and the string-typed amount, which are the least obvious parts of the schema. It adds no detail on the date parameter beyond what the schema already says.

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 gives a specific verb (convert) plus resource (currency amounts at ECB reference rates) and immediately scopes it: latest rate or any day in the last 90 days, up to multiple targets. It is clearly distinguishable from the sibling fx_reference_rates (raw rates) by focusing on conversion of an amount.

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 states the useful context (ECB reference rates, 90-day window, up to 10 targets) and a key exclusion — 'Reference rates, not transaction rates' — which steers an agent away from using it for settlement pricing. It does not, however, explicitly name sibling alternatives such as fx_reference_rates or verify_receipt for receipt checking.

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

All Stablecoin Gateways toolsInspect
Try in Browser
One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources