Documentation
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Overview ¶
Package mcp implements the Model Context Protocol (MCP) client. It supports connecting to MCP servers via stdio transport, listing tools and resources, and invoking tool calls. The SSE transport is not yet implemented and fails cleanly at construction time (see NewClient).
Index ¶
- func RegisterTools(ctx context.Context, client *Client, registry *tool.Registry) (int, error)
- func ToolInfoToDefinitions(client *Client, tools []ToolInfo) []*tool.Definition
- func ToolInfoToJSON(tools []ToolInfo) ([]byte, error)
- type Client
- func (c *Client) CallTool(ctx context.Context, name string, args map[string]any) (any, error)
- func (c *Client) Close() error
- func (c *Client) Connect(ctx context.Context) error
- func (c *Client) Info() ServerInfo
- func (c *Client) ListResources(ctx context.Context) ([]ResourceInfo, error)
- func (c *Client) ListTools(ctx context.Context) ([]ToolInfo, error)
- func (c *Client) ReadResource(ctx context.Context, uri string) ([]ResourceContent, error)
- type ResourceContent
- type ResourceInfo
- type ServerConfig
- type ServerInfo
- type ToolInfo
- type Transport
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func RegisterTools ¶
RegisterTools fetches tools from the MCP server and registers them in the given tool registry. Each MCP tool becomes a tool.Definition whose handler routes calls through the MCP client.
func ToolInfoToDefinitions ¶
func ToolInfoToDefinitions(client *Client, tools []ToolInfo) []*tool.Definition
ToolInfoToDefinitions converts MCP ToolInfo items into tool.Definition items without registering them. Useful for inspection or custom registration.
func ToolInfoToJSON ¶
ToolInfoToJSON converts tool info into a JSON representation suitable for model tool definitions.
Types ¶
type Client ¶
type Client struct {
// contains filtered or unexported fields
}
Client communicates with an MCP server using JSON-RPC 2.0 over stdio.
Concurrency model:
- mu serializes in-flight requests. It is held while writing a request and reading its response. The read honors the per-call context via a read deadline, so it never blocks indefinitely while holding mu.
- Close does NOT acquire mu. It force-kills the subprocess and clears any read deadline, which unblocks any in-flight read so a hung server can be torn down even while a call is stuck. The closed flag is atomic so it can be observed without the lock.
func NewClient ¶
func NewClient(cfg ServerConfig) (*Client, error)
NewClient creates a new MCP client for the given server configuration. For stdio transport, it launches the command as a subprocess on Connect.
The SSE transport is not yet implemented; NewClient rejects it at construction time with a clear error rather than deferring the failure to call time.
func (*Client) Close ¶
Close shuts down the MCP server connection. It force-kills the subprocess and clears any read deadline so that an in-flight call blocked on a hung server is unblocked promptly. Close does not acquire the request mutex, so it can tear down a client even while a call is stuck in a read. Close is idempotent and safe to call multiple times.
func (*Client) Connect ¶
Connect starts the MCP server process and performs the initialize handshake.
func (*Client) Info ¶
func (c *Client) Info() ServerInfo
Info returns the server information from the initialize handshake.
func (*Client) ListResources ¶
func (c *Client) ListResources(ctx context.Context) ([]ResourceInfo, error)
ListResources fetches the available resources from the MCP server.
func (*Client) ReadResource ¶
ReadResource fetches the content of a resource by URI.
type ResourceContent ¶
type ResourceContent struct {
URI string `json:"uri"`
MimeType string `json:"mimeType,omitempty"`
Text string `json:"text,omitempty"`
}
ResourceContent holds the content returned when reading a resource.
type ResourceInfo ¶
type ResourceInfo struct {
URI string `json:"uri"`
Name string `json:"name,omitempty"`
Description string `json:"description,omitempty"`
MimeType string `json:"mimeType,omitempty"`
}
ResourceInfo describes a resource provided by an MCP server.
type ServerConfig ¶
type ServerConfig struct {
Name string `json:"name" yaml:"name"`
Transport Transport `json:"transport" yaml:"transport"`
Command string `json:"command,omitempty" yaml:"command,omitempty"`
Args []string `json:"args,omitempty" yaml:"args,omitempty"`
URL string `json:"url,omitempty" yaml:"url,omitempty"`
}
ServerConfig holds the connection configuration for an MCP server.
type ServerInfo ¶
type ServerInfo struct {
Name string `json:"name"`
Version string `json:"version"`
ProtocolVer string `json:"protocolVersion"`
}
ServerInfo holds the server's initialization response.
Source Files