mcpclient

Documentation

Overview

Package mcpclient provides a Go client that speaks Model Context Protocol (MCP) over stdio to downstream MCP servers running as subprocesses.

Communication uses newline-delimited JSON-RPC 2.0 over the subprocess's stdin (requests) and stdout (responses).

Index

• type Client
  • func NewClient(ctx context.Context, name string, command []string, env []string) (*Client, error)
  • func (c *Client) CallTool(_ context.Context, name string, arguments map[string]any) (*mcp.ToolResult, error)
  • func (c *Client) Close() error
  • func (c *Client) DiscoverTools(_ context.Context) ([]mcp.ToolDef, error)
  • func (c *Client) Name() string
  • func (c *Client) Tools() []mcp.ToolDef

Types

type Client

type Client struct {
	// contains filtered or unexported fields
}

Client manages a connection to a single downstream MCP server subprocess.

func NewClient

func NewClient(ctx context.Context, name string, command []string, env []string) (*Client, error)

NewClient spawns a downstream MCP server as a subprocess and performs the MCP initialize handshake. The command slice must contain at least the program name; additional elements are passed as arguments. The env slice is merged with os.Environ() so the subprocess inherits the current environment plus any overrides.

func (*Client) CallTool

func (c *Client) CallTool(_ context.Context, name string, arguments map[string]any) (*mcp.ToolResult, error)

CallTool invokes a tool on the downstream MCP server by name.

func (*Client) Close

func (c *Client) Close() error

Close terminates the subprocess. It sends SIGTERM first, then SIGKILL after a 5-second timeout if the process hasn't exited.

func (*Client) DiscoverTools

func (c *Client) DiscoverTools(_ context.Context) ([]mcp.ToolDef, error)

DiscoverTools sends a tools/list request and caches the result.

func (*Client) Name

func (c *Client) Name() string

Name returns the human-readable name of this client connection.

func (*Client) Tools

func (c *Client) Tools() []mcp.ToolDef

Tools returns the cached list of tools discovered from the server.