mcp-coinbase

buy_crypto

Buy cryptocurrency on Coinbase with an optional preview. Specify symbol and USD amount; set confirm to true to execute the order.

Instructions

Place a buy order for cryptocurrency on Coinbase. Set confirm to false (default) for a preview, or true to execute. Requires COINBASE_EMAIL and COINBASE_PASSWORD environment variables.

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": {
      "symbol": "<symbol>",
      "amount_usd": "<amount_usd>"
    },
    "name": "buy_crypto"
  }
}

Input Schema

Name	Required	Description
`symbol`	Yes	Cryptocurrency symbol to buy (e.g., "BTC", "ETH")
`confirm`	No	If false, returns preview only. If true, executes the order.
`amount_usd`	Yes	Amount in USD to spend

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Aug 10, 2026

TDQS

A4/5.0

Behavior3/5

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

No annotations are provided, so the description carries the burden. It discloses the environment variable requirements and the preview/execute modes, which adds value. However, it does not mention potential side effects (e.g., irreversible real-money orders, fees, order types) that would be useful for a mutation tool.

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?

Two concise sentences front-load the main purpose, then provide essential details about confirm behavior and environment variables. No wasted words.

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?

The tool has a clear purpose, all parameters are documented in the schema, and the description covers the key behavioral distinction (preview vs execute) and prerequisites. No output schema is provided, so return value details are not required. This is sufficiently complete for a relatively simple buy tool.

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?

The input schema provides 100% coverage with descriptions for symbol, amount_usd, and confirm. The description repeats the confirm behavior but adds no new semantic meaning beyond the schema. Baseline 3 is appropriate.

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 uses a specific verb and resource: 'Place a buy order for cryptocurrency on Coinbase.' This clearly distinguishes it from siblings like sell_crypto (sell) and get_portfolio (read).

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?

The description clearly implies when to use the tool (when buying crypto) and explains the confirm parameter for preview vs execution. It does not explicitly mention alternatives or exclusions, but the context is clear enough for an agent to select it for buy actions.

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

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