Local MCP server

chance-mcp (MIT) is a stdio process for MCP clients that launch local servers. It forwards every JSON-RPC message to https://harness.chance.cc/api/mcp with Authorization: Bearer $CHANCE_API_KEY and returns the reply. It defines no tools of its own: the tool list, schemas and results come from the hosted server. An API key carries both the mcp and wallet scopes, so every hosted tool is available.

Requires Node 18 or later.
Each request times out after 300 seconds.
Clients that support remote HTTP servers can connect to the hosted server directly and sign in with OAuth instead. See Connectors.

Setup

Create an API key

Add the server to your MCP client

{
  "mcpServers": {
    "chance": {
      "command": "npx",
      "args": ["-y", "chance-mcp"],
      "env": { "CHANCE_API_KEY": "chance_sk_live_..." }
    }
  }
}

Claude Desktop

Settings → Developer → Edit Config, add the block to claude_desktop_config.json, and restart Claude Desktop.

Claude Code

claude mcp add chance -e CHANCE_API_KEY=chance_sk_live_... -- npx -y chance-mcp

Cursor and Windsurf

Add the same mcpServers block to the client’s MCP config and reload.

Confirm the connection

Ask the agent to call check_connection. It is free and returns the account, remaining credits and whether the wallet tools are available. Do not use verify_intent as a test: it costs a credit.

Environment

Variable	Required	Default	Description
`CHANCE_API_KEY`	Yes	None	A `chance_sk_live_…` key.
`CHANCE_BASE_URL`	No	`https://harness.chance.cc`	The server to forward to. Messages go to `<CHANCE_BASE_URL>/api/mcp`.

Errors

Condition	JSON-RPC code	Message starts with
`CHANCE_API_KEY` is not set	`-32001`	`CHANCE_API_KEY is not set.` Nothing is sent to the server.
The server rejected the key (HTTP `401`)	`-32001`	`Chance rejected the API key (401).`
Any other HTTP error	`-32000`	`Chance returned HTTP <status>:`
Network failure or timeout	`-32000`	`Could not reach Chance at <base URL>:`

On start the process writes chance-mcp proxying to <endpoint> to stderr.

Tools

The tools are the hosted server’s. See the MCP tool reference. A standing instruction for the agent:

Before you place any order, call verify_intent with my rules as the intent and the exact order payload as the action. Do not execute unless the verdict is ALLOW, and tell me the reasoning when it is not.

Integrate

Chance verification

Payload adapters

HTTP endpoints

Local MCP server

Setup

Environment

Errors

Tools

​Setup

​Environment

​Errors

​Tools

Setup

Environment

Errors

Tools