| 1 | import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js' |
| 2 | import { |
| 3 | CallToolRequestSchema, |
| 4 | ErrorCode, |
| 5 | ListToolsRequestSchema, |
| 6 | McpError, |
| 7 | } from '@modelcontextprotocol/sdk/types.js' |
| 8 | import { Inject, Injectable, Scope } from '@nestjs/common' |
| 9 | import { ContextIdFactory, ModuleRef } from '@nestjs/core' |
| 10 | import { getErrorMessage, zodToJsonSchemaOptions } from '@yikart/common' |
| 11 | import { z, ZodTypeAny } from 'zod' |
| 12 | import { ResultTool } from '../../interfaces' |
| 13 | import { HttpRequest } from '../../interfaces/http-adapter.interface' |
| 14 | import { MCP_TOOL_MONITOR, McpToolMonitor } from '../../interfaces/mcp-tool-monitor.interface' |
| 15 | import { McpRegistryService } from '../mcp-registry.service' |
| 16 | import { McpHandlerBase } from './mcp-handler.base' |
| 17 | |
| 18 | @Injectable({ scope: Scope.REQUEST }) |
| 19 | export class McpToolsHandler extends McpHandlerBase { |
| 20 | constructor( |
| 21 | moduleRef: ModuleRef, |
| 22 | registry: McpRegistryService, |
| 23 | @Inject('MCP_MODULE_ID') private readonly mcpModuleId: string, |
| 24 | @Inject(MCP_TOOL_MONITOR) private readonly toolMonitor: McpToolMonitor, |
| 25 | ) { |
| 26 | super(moduleRef, registry, McpToolsHandler.name) |
| 27 | } |
| 28 | |
| 29 | private buildDefaultContentBlock(result: any) { |
| 30 | return [ |
| 31 | { |
| 32 | type: 'text', |
| 33 | text: JSON.stringify(result), |
| 34 | }, |
| 35 | ] |
| 36 | } |
| 37 | |
| 38 | private formatToolResult(result: any, outputSchema?: ZodTypeAny): any { |
| 39 | if (result && typeof result === 'object' && Array.isArray(result.content)) { |
| 40 | return result |
| 41 | } |
| 42 | |
| 43 | if (outputSchema) { |
| 44 | const validation = outputSchema.safeParse(result) |
| 45 | if (!validation.success) { |
| 46 | throw new McpError( |
| 47 | ErrorCode.InternalError, |
| 48 | `Tool result does not match outputSchema: ${validation.error.message}`, |
| 49 | ) |
| 50 | } |
| 51 | return { |
| 52 | structuredContent: result, |
| 53 | content: this.buildDefaultContentBlock(result), |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | return { |
| 58 | content: this.buildDefaultContentBlock(result), |
| 59 | } |
| 60 | } |
| 61 | |
| 62 | registerHandlers(mcpServer: McpServer, httpRequest: HttpRequest) { |
| 63 | if (this.registry.getTools(this.mcpModuleId).length === 0) { |
| 64 | this.logger.debug('No tools registered, skipping tool handlers') |
| 65 | return |
| 66 | } |
| 67 | |
| 68 | mcpServer.server.setRequestHandler(ListToolsRequestSchema, () => { |
| 69 | const tools = this.registry.getTools(this.mcpModuleId).map((tool) => { |
| 70 | // Create base schema |
| 71 | const toolSchema: Partial<ResultTool> = { |
| 72 | name: tool.metadata.name, |
| 73 | description: tool.metadata.description, |
| 74 | annotations: tool.metadata.annotations, |
| 75 | _meta: tool.metadata._meta, |
| 76 | } |
| 77 | |
| 78 | // Add input schema if defined |
| 79 | if (tool.metadata.parameters) { |
| 80 | toolSchema['inputSchema'] = z.toJSONSchema(tool.metadata.parameters, { |
| 81 | ...zodToJsonSchemaOptions, |
| 82 | io: 'input', |
| 83 | }) as ResultTool['inputSchema'] |
| 84 | } |
| 85 | |
| 86 | // Add output schema if defined, ensuring it has type: 'object' |
| 87 | if (tool.metadata.outputSchema) { |
| 88 | const outputSchema = z.toJSONSchema(tool.metadata.outputSchema, { |
| 89 | ...zodToJsonSchemaOptions, |
| 90 | io: 'output', |
| 91 | }) |
| 92 | |
| 93 | // Create a new object that explicitly includes type: 'object' |
| 94 | const jsonSchema = { |
| 95 | ...outputSchema, |
| 96 | type: 'object', |
| 97 | } |
| 98 | |
| 99 | toolSchema['outputSchema'] = jsonSchema as ResultTool['outputSchema'] |
| 100 | } |
| 101 | |
| 102 | return toolSchema |
| 103 | }) |
| 104 | |
| 105 | return { |
| 106 | tools, |
| 107 | } |
| 108 | }) |
| 109 | |
| 110 | mcpServer.server.setRequestHandler( |
| 111 | CallToolRequestSchema, |
| 112 | async (request) => { |
| 113 | this.logger.debug('CallToolRequestSchema is being called') |
| 114 | |
| 115 | const toolInfo = this.registry.findTool( |
| 116 | this.mcpModuleId, |
| 117 | request.params.name, |
| 118 | ) |
| 119 | |
| 120 | if (!toolInfo) { |
| 121 | throw new McpError( |
| 122 | ErrorCode.MethodNotFound, |
| 123 | `Unknown tool: ${request.params.name}`, |
| 124 | ) |
| 125 | } |
| 126 | |
| 127 | try { |
| 128 | // Validate input parameters against the tool's schema |
| 129 | if (toolInfo.metadata.parameters) { |
| 130 | const validation = toolInfo.metadata.parameters.safeParse( |
| 131 | request.params.arguments || {}, |
| 132 | ) |
| 133 | if (!validation.success) { |
| 134 | throw new McpError( |
| 135 | ErrorCode.InvalidParams, |
| 136 | `Invalid parameters: ${validation.error.message}`, |
| 137 | ) |
| 138 | } |
| 139 | // Use validated arguments to ensure defaults and transformations are applied |
| 140 | request.params.arguments = validation.data |
| 141 | } |
| 142 | |
| 143 | const contextId = ContextIdFactory.getByRequest(httpRequest) |
| 144 | this.moduleRef.registerRequestByContextId(httpRequest, contextId) |
| 145 | |
| 146 | const toolInstance = await this.moduleRef.resolve( |
| 147 | toolInfo.providerClass, |
| 148 | contextId, |
| 149 | { strict: false }, |
| 150 | ) |
| 151 | |
| 152 | const context = this.createContext(mcpServer, request) |
| 153 | |
| 154 | if (!toolInstance) { |
| 155 | throw new McpError( |
| 156 | ErrorCode.MethodNotFound, |
| 157 | `Unknown tool: ${request.params.name}`, |
| 158 | ) |
| 159 | } |
| 160 | this.logger.debug({ toolInfo, request }) |
| 161 | |
| 162 | const result = await toolInstance[toolInfo.methodName]( |
| 163 | request.params.arguments, |
| 164 | context, |
| 165 | httpRequest.raw, |
| 166 | ) |
| 167 | |
| 168 | const transformedResult = this.formatToolResult( |
| 169 | result, |
| 170 | toolInfo.metadata.outputSchema, |
| 171 | ) |
| 172 | |
| 173 | this.logger.debug(transformedResult, 'CallToolRequestSchema result') |
| 174 | |
| 175 | try { |
| 176 | await this.toolMonitor.onToolSuccess(request.params.name) |
| 177 | } |
| 178 | catch (e) { |
| 179 | this.logger.error(e, 'Failed to record tool monitor status') |
| 180 | } |
| 181 | |
| 182 | return transformedResult |
| 183 | } |
| 184 | catch (error) { |
| 185 | this.logger.error(error) |
| 186 | |
| 187 | try { |
| 188 | await this.toolMonitor.onToolError(request.params.name, error) |
| 189 | } |
| 190 | catch {} |
| 191 | |
| 192 | // Re-throw McpErrors (like validation errors) so they are handled by the MCP protocol layer |
| 193 | if (error instanceof McpError) { |
| 194 | throw error |
| 195 | } |
| 196 | const errorMessage = getErrorMessage(error) |
| 197 | // For other errors, return formatted error response |
| 198 | return { |
| 199 | content: [{ type: 'text', text: errorMessage }], |
| 200 | isError: true, |
| 201 | } |
| 202 | } |
| 203 | }, |
| 204 | ) |
| 205 | } |
| 206 | } |
| 207 |