SiteCheck Crypto & Finance

Exchange rates against the US dollar for about 170 fiat

finance_coincap_rates

Read-only

Exchange rates against the US dollar for about 170 fiat currencies and 400+ cryptocurrencies (Coinbase public rates): symbol, name, fiat or crypto, USD value of one unit and units per USD. All rates, a fiat/crypto filter, or one currency by symbol (EUR, BTC, TRY) or name (euro, bitcoin, turkish-lira). Price: $0.002 in USDC per successful call, paid with x402 (Base, Solana or Arc); failed calls are not charged.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "finance_coincap_rates"
  }
}

Input Schema

Name	Required	Description	Default
`id`	No	Currency symbol (EUR, BTC) or name (euro, bitcoin, turkish-lira); omit for all
`type`	No	fiat or crypto (filter for the full list)

Output Schema

Name	Required	Description	Default
`base`	No
`count`	No
`source`	No
`results`	No
`checkedAt`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 23, 2026

TDQS

A4.1/5.0

Behavior5/5

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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses a paid-call model: $0.002 in USDC per successful call over x402 on Base, Solana or Arc, with failed calls not charged. That is exactly the kind of cost and settlement information an agent needs before invoking, and it does not conflict with the read-only annotation.

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?

Two tight sentences, front-loaded with the resource and scope, then the cost model. The only redundancy is repeating the identifier examples already present in the schema, which costs a few words without harming clarity.

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?

For a zero-required-parameter read tool with an output schema and populated annotations, the description covers scope, accepted inputs, cost, and settlement rails. Nothing an agent needs in order to decide whether and how to call it is 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 description's examples (EUR, BTC, TRY, euro, bitcoin, turkish-lira, omit for all) duplicate what the id property already documents rather than extending it, such as case sensitivity or behavior on an unknown symbol. Baseline 3 is appropriate when the schema already carries parameter meaning.

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?

The description names a precise resource and scope: USD exchange rates for ~170 fiat currencies and 400+ cryptocurrencies sourced from Coinbase public rates, plus the exact fields returned (symbol, name, fiat/crypto flag, USD value, units per USD). That is enough to distinguish it from market-data siblings, but it never names an adjacent tool (e.g. coinbase spot exchange or coinbase assets) to explicitly rule out confusion.

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 enumerates the three supported call shapes: full list (omit id), fiat/crypto filter via the type parameter, or a single currency by symbol/name. That gives clear operating context, but there is no explicit guidance about when to prefer this over a sibling ticker or spot-price tool, nor any prerequisite notes beyond the payment model.

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

All SiteCheck Crypto & Finance tools Inspect

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