language-server-mcp

Instructions

Implementation Reference

• src/index.ts:481-543 (handler)

  The core handler function that implements the 'get_completions' tool logic. It extracts parameters, ensures the language server is running, opens the document, sends a completion request to the LSP server, and formats the response.

  private async handleGetCompletions(args: any): Promise<any> {
    const { languageId, filePath, content, line, character, projectRoot } = args;
    console.log(`[handleGetCompletions] Processing request for ${languageId}`);
    
    const server = await this.getOrCreateServer(languageId, projectRoot);
    const actualRoot = server.workspaceRoot;
  
    const absolutePath = isAbsolute(filePath) ? filePath : join(actualRoot, filePath);
    const uri = `file://${absolutePath}`;
  
    // Ensure directory exists
    const dir = dirname(absolutePath);
    if (!existsSync(dir)) {
      mkdirSync(dir, { recursive: true });
    }
  
    const textDocument: TextDocumentItem = {
      uri,
      languageId,
      version: 1,
      text: content,
    };
  
    console.log(`[handleGetCompletions] Sending document to server:`, textDocument);
    await server.connection.sendNotification('textDocument/didOpen', {
      textDocument,
    } as DidOpenTextDocumentParams);
  
    try {
      console.log(`[handleGetCompletions] Requesting completions`);
      const completionParams: CompletionParams = {
        textDocument: { uri },
        position: { line, character },
      };
  
      const completions: CompletionItem[] | null = await server.connection.sendRequest(
        'textDocument/completion',
        completionParams
      );
  
      console.log(`[handleGetCompletions] Received completions:`, completions);
      return {
        content: [
          {
            type: 'text',
            text: completions
              ? JSON.stringify(completions, null, 2)
              : 'No completions available',
          },
        ],
      };
    } catch (error) {
      console.error('[handleGetCompletions] Request failed:', error);
      return {
        content: [
          {
            type: 'text',
            text: 'Failed to get completions',
          },
        ],
        isError: true,
      };
    }

• src/index.ts:325-358 (registration)

  The tool registration object returned in the listTools response, defining the name, description, and input schema for 'get_completions'.

  {
    name: 'get_completions',
    description: 'Get completion suggestions for a position in a document',
    inputSchema: {
      type: 'object',
      properties: {
        languageId: { 
          type: 'string',
          description: 'The language identifier (e.g., "typescript", "javascript")'
        },
        filePath: { 
          type: 'string',
          description: 'Absolute or relative path to the source file'
        },
        content: { 
          type: 'string',
          description: 'The current content of the file'
        },
        line: { 
          type: 'number',
          description: 'Zero-based line number for completion position'
        },
        character: { 
          type: 'number',
          description: 'Zero-based character offset for completion position'
        },
        projectRoot: { 
          type: 'string',
          description: 'Important: Root directory of the project for resolving imports and node_modules where the tsconfig.json or jsconfig.json is located'
        },
      },
      required: ['languageId', 'filePath', 'content', 'line', 'character', 'projectRoot'],
    },
  },

• src/index.ts:398-400 (registration)

  The dispatch case in the callTool request handler that routes 'get_completions' calls to the handleGetCompletions method.

  case 'get_completions':
    result = await this.handleGetCompletions(args);
    break;

• src/index.ts:328-357 (schema)

  The input schema defining the parameters expected by the 'get_completions' tool.

  inputSchema: {
    type: 'object',
    properties: {
      languageId: { 
        type: 'string',
        description: 'The language identifier (e.g., "typescript", "javascript")'
      },
      filePath: { 
        type: 'string',
        description: 'Absolute or relative path to the source file'
      },
      content: { 
        type: 'string',
        description: 'The current content of the file'
      },
      line: { 
        type: 'number',
        description: 'Zero-based line number for completion position'
      },
      character: { 
        type: 'number',
        description: 'Zero-based character offset for completion position'
      },
      projectRoot: { 
        type: 'string',
        description: 'Important: Root directory of the project for resolving imports and node_modules where the tsconfig.json or jsconfig.json is located'
      },
    },
    required: ['languageId', 'filePath', 'content', 'line', 'character', 'projectRoot'],
  },