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lkcair

yfinance-ai MCP server

by lkcair

get_crypto_price

Read-onlyIdempotent

Fetch current cryptocurrency price and 24h market data by symbol, including market cap and volume, to support crypto quotes in AI clients.

Instructions

Get cryptocurrency price and market data.

Args: symbol: Crypto symbol (e.g., 'BTC', 'ETH', 'bitcoin', 'ethereum', 'BTC-USD')

Returns: Current price, 24h change, market cap, volume, and key metrics

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
symbolYes

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.1.0

TDQS

A3.6/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=true, covering the safety and idempotency profile. The description adds no further behavioral context such as data freshness/latency or rate limits, so it does not go meaningfully beyond the annotations.

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 is front-loaded in the first sentence, followed by cleanly separated Args and Returns sections. The Returns block is mildly redundant given an output schema exists, but nothing is bloated.

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 one-parameter query tool with a full output schema and rich annotations, the definition covers what an agent needs. The only minor gap is the absence of any note on quote freshness or rate behavior, which is not critical for calling it correctly.

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% for the single 'symbol' param, so the description carries the burden — and it does so well by giving concrete accepted formats ('BTC', 'ETH', 'bitcoin', 'ethereum', 'BTC-USD'). This clarifies that tickers, names, and pair strings are all valid, which the bare schema does not.

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+resource: 'Get cryptocurrency price and market data.' The resource ('cryptocurrency') cleanly distinguishes it from siblings like get_stock_price, get_commodity_price, and get_forex_rate, though it never names those alternatives explicitly.

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 implied by the resource scope — an agent will infer this is the tool for crypto quotes — but there is no explicit when-to-use guidance and no exclusions against the many adjacent price tools (get_stock_price, get_commodity_price).

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