MCP Dev MCP

import { ResultAsync, okAsync, errAsync } from "neverthrow"; import { execCommand, parseJson } from "../utils/result.js"; import { createRequire } from "module"; import type { InspectorError, TargetServer, ToolsListResult, ToolCallResult, ResourcesListResult, ResourceReadResult, PromptsListResult, PromptGetResult, } from "../types.js"; const require = createRequire(import.meta.url); const inspectorPath = require.resolve("@modelcontextprotocol/inspector/cli/build/cli.js"); /** * Inspector CLI method types */ type InspectorMethod = | "tools/list" | "tools/call" | "resources/list" | "resources/read" | "prompts/list" | "prompts/get"; /** * Build CLI arguments for Inspector */ function buildCliArgs( method: InspectorMethod, target: TargetServer, methodArgs?: Record<string, unknown> ): string[] { const args: string[] = [inspectorPath, "--cli"]; // Add target (command or URL) - Must be first to avoid being consumed by variadic args args.push(target.target); // Add method args.push("--method", method); // Add transport if specified if (target.transport) { args.push("--transport", target.transport); } // Add environment variables if (target.env) { for (const [key, value] of Object.entries(target.env)) { args.push("-e", `${key}=${value}`); } } // Add method specific arguments if (methodArgs) { if (method === "tools/call") { const { name, arguments: toolArgs } = methodArgs as { name: string, arguments: Record<string, unknown> }; args.push("--tool-name", name); if (toolArgs) { for (const [key, value] of Object.entries(toolArgs)) { const val = typeof value === 'string' ? value : JSON.stringify(value); args.push("--tool-arg", `${key}=${val}`); } } } else if (method === "resources/read") { const { uri } = methodArgs as { uri: string }; args.push("--uri", uri); } else if (method === "prompts/get") { const { name, arguments: promptArgs } = methodArgs as { name: string, arguments: Record<string, string> }; args.push("--prompt-name", name); if (promptArgs) { for (const [key, value] of Object.entries(promptArgs)) { args.push("--prompt-args", `${key}=${value}`); } } } } return args; } /** * Run Inspector CLI command and return parsed result */ function runInspectorCli<T>( method: InspectorMethod, target: TargetServer, methodArgs?: Record<string, unknown>, timeoutMs?: number ): ResultAsync<T, InspectorError> { const args = buildCliArgs(method, target, methodArgs); // Use node directly with shell: false to avoid argument parsing issues on Windows return execCommand("node", args, { timeoutMs: timeoutMs ?? 60000, shell: false }).andThen( (output) => { // Inspector CLI outputs JSON to stdout const trimmedOutput = output.trim(); const jsonStr = trimmedOutput || "{}"; const parseResult = parseJson<T>(jsonStr); if (parseResult.isOk()) { return okAsync(parseResult.value); } return errAsync(parseResult.error); } ); } /** * List tools from target MCP server */ export function listTools( target: TargetServer, timeoutMs?: number ): ResultAsync<ToolsListResult, InspectorError> { return runInspectorCli<ToolsListResult>("tools/list", target, undefined, timeoutMs); } /** * Call a tool on target MCP server */ export function callTool( target: TargetServer, toolName: string, toolArgs?: Record<string, unknown>, timeoutMs?: number ): ResultAsync<ToolCallResult, InspectorError> { return runInspectorCli<ToolCallResult>( "tools/call", target, { name: toolName, arguments: toolArgs ?? {} }, timeoutMs ); } /** * List resources from target MCP server */ export function listResources( target: TargetServer, timeoutMs?: number ): ResultAsync<ResourcesListResult, InspectorError> { return runInspectorCli<ResourcesListResult>("resources/list", target, undefined, timeoutMs); } /** * Read a resource from target MCP server */ export function readResource( target: TargetServer, uri: string, timeoutMs?: number ): ResultAsync<ResourceReadResult, InspectorError> { return runInspectorCli<ResourceReadResult>( "resources/read", target, { uri }, timeoutMs ); } /** * List prompts from target MCP server */ export function listPrompts( target: TargetServer, timeoutMs?: number ): ResultAsync<PromptsListResult, InspectorError> { return runInspectorCli<PromptsListResult>("prompts/list", target, undefined, timeoutMs); } /** * Get a prompt from target MCP server */ export function getPrompt( target: TargetServer, promptName: string, promptArgs?: Record<string, string>, timeoutMs?: number ): ResultAsync<PromptGetResult, InspectorError> { return runInspectorCli<PromptGetResult>( "prompts/get", target, { name: promptName, arguments: promptArgs ?? {} }, timeoutMs ); }