116 lines
3.6 KiB
Ruby
116 lines
3.6 KiB
Ruby
# frozen_string_literal: true
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module MCP
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class Client
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# Initializes a new MCP::Client instance.
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#
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# @param transport [Object] The transport object to use for communication with the server.
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# The transport should be a duck type that responds to `send_request`. See the README for more details.
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#
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# @example
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# transport = MCP::Client::HTTP.new(url: "http://localhost:3000")
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# client = MCP::Client.new(transport: transport)
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def initialize(transport:)
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@transport = transport
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end
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# The user may want to access additional transport-specific methods/attributes
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# So keeping it public
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attr_reader :transport
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# Returns the list of tools available from the server.
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# Each call will make a new request – the result is not cached.
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#
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# @return [Array<MCP::Client::Tool>] An array of available tools.
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#
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# @example
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# tools = client.tools
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# tools.each do |tool|
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# puts tool.name
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# end
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def tools
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response = transport.send_request(request: {
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jsonrpc: JsonRpcHandler::Version::V2_0,
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id: request_id,
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method: "tools/list",
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})
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response.dig("result", "tools")&.map do |tool|
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Tool.new(
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name: tool["name"],
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description: tool["description"],
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input_schema: tool["inputSchema"],
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)
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end || []
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end
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# Returns the list of resources available from the server.
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# Each call will make a new request – the result is not cached.
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#
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# @return [Array<Hash>] An array of available resources.
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def resources
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response = transport.send_request(request: {
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jsonrpc: JsonRpcHandler::Version::V2_0,
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id: request_id,
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method: "resources/list",
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})
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response.dig("result", "resources") || []
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end
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# Calls a tool via the transport layer and returns the full response from the server.
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#
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# @param tool [MCP::Client::Tool] The tool to be called.
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# @param arguments [Object, nil] The arguments to pass to the tool.
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# @return [Hash] The full JSON-RPC response from the transport.
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#
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# @example
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# tool = client.tools.first
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# response = client.call_tool(tool: tool, arguments: { foo: "bar" })
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# structured_content = response.dig("result", "structuredContent")
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#
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# @note
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# The exact requirements for `arguments` are determined by the transport layer in use.
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# Consult the documentation for your transport (e.g., MCP::Client::HTTP) for details.
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def call_tool(tool:, arguments: nil)
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transport.send_request(request: {
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jsonrpc: JsonRpcHandler::Version::V2_0,
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id: request_id,
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method: "tools/call",
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params: { name: tool.name, arguments: arguments },
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})
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end
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# Reads a resource from the server by URI and returns the contents.
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#
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# @param uri [String] The URI of the resource to read.
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# @return [Array<Hash>] An array of resource contents (text or blob).
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def read_resource(uri:)
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response = transport.send_request(request: {
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jsonrpc: JsonRpcHandler::Version::V2_0,
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id: request_id,
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method: "resources/read",
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params: { uri: uri },
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})
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response.dig("result", "contents") || []
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end
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private
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def request_id
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SecureRandom.uuid
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end
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class RequestHandlerError < StandardError
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attr_reader :error_type, :original_error, :request
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def initialize(message, request, error_type: :internal_error, original_error: nil)
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super(message)
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@request = request
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@error_type = error_type
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@original_error = original_error
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end
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end
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end
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end
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