> ## Documentation Index > Fetch the complete documentation index at: https://docs.eco.com/llms.txt > Use this file to discover all available pages before exploring further. # MCP server > Connect coding agents to Sauce tools for compiling, simulating, building and sending transactions. The Sauce MCP server connects a coding agent to the SDK through the [Model Context Protocol](https://modelcontextprotocol.io). Start it with `sauce mcp`, or let your agent start it from its configuration. Use [AI agents](https://docs.eco.com/sauce-sdk/ai-agents.md) to understand the workflow from a request to a program. This section covers the server's tools, configuration and wallet access. ## Connect your agent Follow [Installation](https://docs.eco.com/sauce-sdk/installation.md#add-the-mcp-server-to-your-agent) for Node.js requirements and configuration for Claude Code, Codex, Cursor, VS Code, Gemini CLI or Claude Desktop. Project configuration can pin the server to a specific package version. Once configured, ask the agent to list its `sauce_` tools. The default local server lists 27 tools. A server started with `--no-stores`, or over HTTP, lists 18. See [which tools a server lists](https://docs.eco.com/sauce-sdk/mcp/tools.md#which-tools-a-server-lists). ## What the server provides | Capability | What you can do | | - | - | | Program tools | Look up token and protocol names, compile programs, and simulate them against chain state | | Transaction tools | Build unsigned cooks, inspect their contents, and broadcast transactions signed by a wallet | | Agent skills | Read SauceScript guidance and integration patterns through tools or `sauce://skills/` resources | | Program prompt | Use `sauce_write_program` to guide the agent through writing and checking a program | | Local wallets and Pot records | List local wallets, enable signing through a password source, and track deployed Pots over stdio | [MCP tools](https://docs.eco.com/sauce-sdk/mcp/tools.md) documents the inputs and outputs. [AI agents](https://docs.eco.com/sauce-sdk/ai-agents.md#from-a-request-to-an-unsigned-transaction) explains the program-writing workflow. ## Choose a transport A local agent usually starts the server over **stdio**, communicating through the process's standard input and output. Use **HTTP** when agents need to connect to a shared server by URL. | | stdio (default) | HTTP (`--http `) | | - | - | - | | Started by | Your coding agent | You, as a long-running process | | Connection | Local process; stdout carries only the MCP protocol | Stateless Streamable HTTP at `/mcp` | | Tools | 27 by default; 20 with `--no-wallets`; 18 with `--no-stores` | 18 | | Wallets | `~/.sauce/wallets` by default | No wallet tools or signing | | Pot records | `~/.sauce/pots` by default | No Pot store | | Program files | Accepts a local `path` | Accepts source text and `modules`; refuses `path` | | Caller-provided RPC URLs | Used as supplied | HTTPS and public-address checks by default | [Local server storage](https://docs.eco.com/sauce-sdk/mcp/local-server.md) covers the stdio stores. [Self-hosting over HTTP](https://docs.eco.com/sauce-sdk/mcp/self-hosting.md) covers authentication, endpoint restrictions and deployment. ## Wallet access Transaction-building tools return unsigned transactions. No tool input accepts a private key, seed or password, and no result returns one. You can sign with your own wallet or [a separate wallet MCP server](https://docs.eco.com/sauce-sdk/mcp/external-wallets.md). The local stdio server also exposes your Sauce wallet directory. A password source enables its signing tools; an agent can enable them by naming a source the server can read. Start with `--no-wallets` to remove wallet tools, or `--no-stores` to remove wallet tools and Pot records. See [Wallets over stdio](https://docs.eco.com/sauce-sdk/mcp/wallets.md) and [Agents, wallets and keys](https://docs.eco.com/sauce/security-considerations.md#agents-wallets-and-keys). ## Chain access A tool selects an endpoint from its `rpcUrl` input, then the server's `--config` file, then a built-in public endpoint. RPC URLs are not included in results, logs or error messages. See [How a tool reaches a chain](https://docs.eco.com/sauce-sdk/mcp/tools.md#how-a-tool-reaches-a-chain) for the full order and offline behavior. The server builds and sends transactions on Ethereum, Base, Arc and Solana, and on the testnets Arc Testnet, Base Sepolia, Ethereum Sepolia, Solana Devnet and Solana Testnet. On preview chains, compiling and reading work; simulation also requires the release's engine and Kitchen to be deployed. Transaction building is refused. See [supported and preview chains](https://docs.eco.com/sauce-sdk/mcp/tools.md#supported-and-preview-chains). ## Runtime packages The server needs the MCP SDK and `zod` at the versions pinned by the package. It uses matching project dependencies when available, or installs them in `~/.sauce/runtime/` on first use. `sauce mcp setup` prepares this directory during setup. Offline startup requires those dependencies to be installed already. Use [`sauce runtime`](https://docs.eco.com/sauce-sdk/cli/runtime) to inspect or install runtime packages. For startup failures, see [MCP setup troubleshooting](https://docs.eco.com/sauce-sdk/operating/troubleshooting.md#mcp-setup). ## Next steps * [MCP tools](https://docs.eco.com/sauce-sdk/mcp/tools.md): look up each tool's inputs and results. * [Wallets over stdio](https://docs.eco.com/sauce-sdk/mcp/wallets.md): configure local signing and spending policies. * [External wallets](https://docs.eco.com/sauce-sdk/mcp/external-wallets.md): sign through a separate wallet server. * [Self-hosting over HTTP](https://docs.eco.com/sauce-sdk/mcp/self-hosting.md): run a shared server. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.