Moralis MCP Server

Instructions

Implementation Reference

• src/utils/execute-api-tool.ts:34-252 (handler)

  The primary handler function that implements the execution logic for all EVM API tools prefixed with 'evm_', including 'evm_getwalletapprovals'. It validates user arguments against the tool's inputSchema using Zod, constructs the HTTP request (URL, params, headers, body) based on the OpenAPI-derived definition, applies API keys for authentication, calls the Moralis API via axios, and formats the JSON response for MCP.
  export async function executeApiTool( toolName: string, definition: McpToolDefinition, toolArgs: JsonObject, allSecuritySchemes: Record<string, any>, token?: string, ): Promise<CallToolResult> { try { // Validate arguments against the input schema let validatedArgs: JsonObject; try { const zodSchema = getZodSchemaFromJsonSchema( definition.inputSchema, toolName, ); const argsToParse = typeof toolArgs === 'object' && toolArgs !== null ? toolArgs : {}; validatedArgs = zodSchema.parse(argsToParse); } catch (error: unknown) { if (error instanceof ZodError) { const validationErrorMessage = `Invalid arguments for tool '${toolName}': ${error.errors.map((e) => `${e.path.join('.')} (${e.code}): ${e.message}`).join(', ')}`; return { content: [{ type: 'text', text: validationErrorMessage }] }; } else { const errorMessage = error instanceof Error ? error.message : String(error); return { content: [ { type: 'text', text: `Internal error during validation setup: ${errorMessage}`, }, ], }; } } // Prepare URL, query parameters, headers, and request body let urlPath = definition.pathTemplate; const queryParams: Record<string, any> = {}; const headers: Record<string, string> = { Accept: 'application/json', 'X-Moralis-Platform': 'MCP', }; let requestBodyData: any = undefined; // Apply parameters to the URL path, query, or headers definition.executionParameters.forEach((param) => { const value = validatedArgs[param.name]; if (typeof value !== 'undefined' && value !== null) { if (param.in === 'path') { urlPath = urlPath.replace( `{${param.name}}`, encodeURIComponent(String(value)), ); } else if (param.in === 'query') { queryParams[param.name] = value; } else if (param.in === 'header') { headers[param.name.toLowerCase()] = String(value); } } }); // Ensure all path parameters are resolved if (urlPath.includes('{')) { throw new Error(`Failed to resolve path parameters: ${urlPath}`); } // Construct the full URL const requestUrl = `${definition.baseUrl}${urlPath}`; // Handle request body if needed if ( definition.requestBodyContentType && typeof validatedArgs['requestBody'] !== 'undefined' ) { requestBodyData = validatedArgs['requestBody']; headers['content-type'] = definition.requestBodyContentType; } // Apply security requirements if available // Security requirements use OR between array items and AND within each object const appliedSecurity = definition.securityRequirements?.find((req) => { // Try each security requirement (combined with OR) return Object.entries(req).every(([schemeName, scopesArray]) => { const scheme = allSecuritySchemes[schemeName]; if (!scheme) return false; // API Key security (header, query, cookie) if (scheme.type === 'apiKey') { return !!token || !!Config.MORALIS_API_KEY; } return false; }); }); // If we found matching security scheme(s), apply them if (appliedSecurity) { // Apply each security scheme from this requirement (combined with AND) for (const [schemeName, scopesArray] of Object.entries(appliedSecurity)) { const scheme = allSecuritySchemes[schemeName]; // API Key security if (scheme?.type === 'apiKey') { const apiKey = token || Config.MORALIS_API_KEY; if (apiKey) { if (scheme.in === 'header') { headers[scheme.name.toLowerCase()] = apiKey; console.error( `Applied API key '${schemeName}' in header '${scheme.name}'`, ); } } } } } // Log warning if security is required but not available else if (definition.securityRequirements?.length > 0) { // First generate a more readable representation of the security requirements const securityRequirementsString = definition.securityRequirements .map((req) => { const parts = Object.entries(req) .map(([name, scopesArray]) => { const scopes = scopesArray as string[]; if (scopes.length === 0) return name; return `${name} (scopes: ${scopes.join(', ')})`; }) .join(' AND '); return `[${parts}]`; }) .join(' OR '); console.warn( `Tool '${toolName}' requires security: ${securityRequirementsString}, but no suitable credentials found.`, ); } // Prepare the axios request configuration const config: AxiosRequestConfig = { method: definition.method.toUpperCase(), url: requestUrl, params: queryParams, headers: headers, ...(requestBodyData !== undefined && { data: requestBodyData }), }; // Log request info to stderr (doesn't affect MCP output) console.error( `Executing tool "${toolName}": ${config.method} ${config.url}`, ); // Execute the request const response = await axios(config); // Process and format the response let responseText = ''; const contentType = response.headers['content-type']?.toLowerCase() || ''; // Handle JSON responses if ( contentType.includes('application/json') && typeof response.data === 'object' && response.data !== null ) { try { responseText = JSON.stringify(response.data, null, 2); } catch (e) { responseText = '[Stringify Error]'; } } // Handle string responses else if (typeof response.data === 'string') { responseText = response.data; } // Handle other response types else if (response.data !== undefined && response.data !== null) { responseText = String(response.data); } // Handle empty responses else { responseText = `(Status: ${response.status} - No body content)`; } // Return formatted response return { content: [ { type: 'text', text: `API Response (Status: ${response.status}):\n${responseText}`, }, ], }; } catch (error: unknown) { // Handle errors during execution let errorMessage: string; // Format Axios errors specially if (axios.isAxiosError(error)) { errorMessage = formatApiError(error); } // Handle standard errors else if (error instanceof Error) { errorMessage = error.message; } // Handle unexpected error types else { errorMessage = `Unexpected error: ${String(error)}`; } // Log error to stderr console.error( `Error during execution of tool '${toolName}':`, errorMessage, ); // Return error message to client return { content: [{ type: 'text', text: errorMessage }] }; } }
• src/server.ts:26-44 (registration)

  Dynamically maps tool definitions for 'evm_' prefixed tools (including 'evm_getwalletapprovals') by fetching and dereferencing the Moralis EVM OpenAPI spec, extracting tools via extractToolsFromApi, applying prefix and blacklist, and creating the toolDefinitionMap used for MCP tool listing and calling.
  async function mapToolDefinitions(config: SchemaConfig) { const spec = (await getSpec(config.specUrl)) as OpenAPIV3DocumentX; const api = (await SwaggerParser.dereference(spec)) as OpenAPIV3DocumentX; const tools = extractToolsFromApi(api, config.prefix); const blacklist = Array.isArray(api['x-mcp-blacklist']) ? api['x-mcp-blacklist'].map((e) => `${config.prefix}${e.toLowerCase()}`) : []; const toolDefinitionMap: Record<string, McpToolDefinition> = {}; for (const tool of tools) { if (blacklist.includes(tool.name)) continue; toolDefinitionMap[tool.name] = { ...tool, baseUrl: config.baseUrl, }; } return toolDefinitionMap; }
• src/server.ts:96-120 (registration)

  Registers the MCP 'tools/call' request handler, which dispatches calls to 'evm_getwalletapprovals' (and all other tools) by looking up the name in toolDefinitionMap and invoking the executeApiTool handler.
  server.setRequestHandler( CallToolRequestSchema, async (request: CallToolRequest, c): Promise<CallToolResult> => { const { name: toolName, arguments: toolArgs } = request.params; const toolDefinition = toolDefinitionMap[toolName]; if (!toolDefinition) { console.error(`Error: Unknown tool requested: ${toolName}`); return { content: [ { type: 'text', text: `Error: Unknown tool requested: ${toolName}`, }, ], }; } return executeApiTool( toolName, toolDefinition, toolArgs ?? {}, securitySchemes, c.authInfo?.token, ); }, );
• src/parser/extract-tools.ts:101-180 (schema)

  Generates the inputSchema (JSON Schema) for MCP tool definitions, including 'evm_getwalletapprovals', by combining path/query/header parameters and requestBody from the OpenAPI operation object. This schema is used for tool description in listTools and Zod validation in executeApiTool.
  export function generateInputSchemaAndDetails( operation: OpenAPIV3.OperationObject, ): { inputSchema: JSONSchema7 | boolean; parameters: OpenAPIV3.ParameterObject[]; requestBodyContentType?: string; } { const properties: { [key: string]: JSONSchema7 | boolean } = {}; const required: string[] = []; // Process parameters const allParameters: OpenAPIV3.ParameterObject[] = Array.isArray( operation.parameters, ) ? operation.parameters.map((p) => p as OpenAPIV3.ParameterObject) : []; allParameters.forEach((param) => { if (!param.name || !param.schema) return; const paramSchema = mapOpenApiSchemaToJsonSchema( param.schema as OpenAPIV3.SchemaObject, ); if (typeof paramSchema === 'object') { paramSchema.description = param.description || paramSchema.description; } properties[param.name] = paramSchema; if (param.required) required.push(param.name); }); // Process request body (if present) let requestBodyContentType: string | undefined = undefined; if (operation.requestBody) { const opRequestBody = operation.requestBody as OpenAPIV3.RequestBodyObject; const jsonContent = opRequestBody.content?.['application/json']; const firstContent = opRequestBody.content ? Object.entries(opRequestBody.content)[0] : undefined; if (jsonContent?.schema) { requestBodyContentType = 'application/json'; const bodySchema = mapOpenApiSchemaToJsonSchema( jsonContent.schema as OpenAPIV3.SchemaObject, ); if (typeof bodySchema === 'object') { bodySchema.description = opRequestBody.description || bodySchema.description || 'The JSON request body.'; } properties['requestBody'] = bodySchema; if (opRequestBody.required) required.push('requestBody'); } else if (firstContent) { const [contentType] = firstContent; requestBodyContentType = contentType; properties['requestBody'] = { type: 'string', description: opRequestBody.description || `Request body (content type: ${contentType})`, }; if (opRequestBody.required) required.push('requestBody'); } } // Combine everything into a JSON Schema const inputSchema: JSONSchema7 = { type: 'object', properties, ...(required.length > 0 && { required }), }; return { inputSchema, parameters: allParameters, requestBodyContentType }; }
• src/parser/extract-tools.ts:17-93 (helper)

  Core helper that iterates OpenAPI paths/operations to create McpToolDefinition objects for all tools, including deriving 'evm_getwalletapprovals' from the corresponding operationId in the Moralis spec.
  export function extractToolsFromApi( api: OpenAPIV3DocumentX, prefix?: string ): McpToolDefinition[] { const tools: McpToolDefinition[] = []; const usedNames = new Set<string>(); const globalSecurity = api.security || []; if (!api.paths) return tools; for (const [path, pathItem] of Object.entries(api.paths)) { if (!pathItem) continue; for (const method of Object.values(OpenAPIV3.HttpMethods)) { const operation = pathItem[method]; if (!operation) continue; // Generate a unique name for the tool let baseName = operation.operationId || generateOperationId(method, path); if (!baseName) continue; // Sanitize the name to be MCP-compatible (only a-z, 0-9, _, -) baseName = baseName .replace(/\./g, '_') .replace(/[^a-z0-9_-]/gi, '_') .toLowerCase(); let finalToolName = baseName; let counter = 1; while (usedNames.has(finalToolName)) { finalToolName = `${baseName}_${counter++}`; } usedNames.add(finalToolName); // Get or create a description const description = operation.description || operation.summary || `Executes ${method.toUpperCase()} ${path}`; const prompt = operation['x-mcp-prompt']; // Generate input schema and extract parameters const { inputSchema, parameters, requestBodyContentType } = generateInputSchemaAndDetails(operation); // Extract parameter details for execution const executionParameters = parameters.map((p) => ({ name: p.name, in: p.in, })); // Determine security requirements const securityRequirements = operation.security === null ? globalSecurity : operation.security || globalSecurity; // Create the tool definition tools.push({ name: prefix + finalToolName, description, inputSchema, method, pathTemplate: path, parameters, executionParameters, requestBodyContentType, securityRequirements, operationId: baseName, prompt, }); } } return tools; }