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Declare upstream MCP servers for the Fentaris proxy
Use mcp(...) for new applications. It creates an McpServer wrapper around a transport and optionally configures display metadata, credentials, env injection, and isolation.

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Quick Start

import { mcp, stdio } from "@fentaris/core";

const filesystem = mcp("filesystem", {
  displayName: "Filesystem",
  transport: stdio({
    command: "npx",
    args: ["-y", "@modelcontextprotocol/server-filesystem", "./demo-files"],
  }),
});

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Options

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name

Server identifier. It becomes the prefix for proxied tool names.
Server names must be stable and must not include __.

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displayName

Human-readable label used in tool titles.

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transport

Transport implementation used to connect to the upstream MCP server. 
transport: stdio({
  command: "npx",
  args: ["-y", "@modelcontextprotocol/server-filesystem", "./demo-files"],
})

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env

Static env map or resolver function by user. 
env: (user) => ({
  USER_ID: user.id ?? "anonymous",
})

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auth

Credential binding used when the server needs bearer or header auth.

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isolation

Optional isolation runtime for user-aware queueing or process isolation.

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Methods

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listTools(params?, user?)

Lists tools for the given user.

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callTool(params, user?)

Calls a tool for the given user.

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listResources(params?, user?)

Lists resources for the given user. Returns an empty resources array when the underlying transport does not implement resource listing.

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readResource(params, user?)

Reads a resource for the given user. Throws when the underlying transport does not implement resource reading.

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listResourceTemplates(params?, user?)

Lists resource templates for the given user. Returns an empty resourceTemplates array when unsupported.

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listPrompts(params?, user?)

Lists prompts for the given user. Returns an empty prompts array when unsupported.

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getPrompt(params, user?)

Gets a prompt for the given user. Throws when unsupported.

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complete(params, user?)

Forwards MCP argument completion for prompt and resource references. Throws when unsupported.

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supportsResources(), supportsPrompts(), supportsCompletions()

Returns whether the configured transport exposes the corresponding optional methods. McpProxy uses these checks to advertise downstream capabilities.

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close()

Closes all transports, including user-specific ones.

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Low-Level Constructor

The class constructor is available for advanced integrations: 
import { McpServer } from "@fentaris/core";

const server = new McpServer({
  name: "filesystem",
  transport,
});
For normal applications, prefer mcp(name, options).